Perinatology (High-Risk Pregnancy) Department

What our perinatology unit covers — and who it is for

Perinatology — maternal fetal medicine, hyphenated in some journals as maternal-fetal medicine — is the sub-specialty that looks after pregnancies where something needs closer attention than routine antenatal care provides: the mother has a medical condition, a scan or screening test has raised a question about the baby, the pregnancy is a twin or higher-order one, or the obstetric history contains an event that changes how this pregnancy is managed. It is the diagnostic and surveillance end of obstetrics, and most of its work is imaging.

Two things are worth saying at the outset, because both are widely misunderstood. A high risk pregnancy is a management label, not a prognosis — it describes how closely a pregnancy is watched, not how it ends, and the large majority of high-risk pregnancies produce a healthy baby. And a great deal of what perinatology does is rule things out: most findings referred for a specialist opinion turn out to be normal variants or isolated markers of no consequence.

At Acıbadem International the work is organised into five strands.

• Screening and diagnosis — first-trimester combined screening, cell-free DNA testing, the detailed anomaly scan, and the invasive tests that confirm or exclude a genetic diagnosis when screening raises one.
• Fetal growth and wellbeing — serial growth scans, Doppler studies of the umbilical and fetal circulations, amniotic fluid assessment, and the surveillance that decides when a baby is safer out than in.
• The placenta and cord — position, invasion and cord insertion, including the placenta accreta spectrum, which this region sees more of than most.
• Multiple pregnancy — chorionicity, the complications specific to shared placentas, and the fetal therapy that some of them need.
• Maternal medicine — pregnancy in women with thyroid, autoimmune, cardiac, kidney, metabolic or clotting disorders, managed jointly with the specialty concerned.

Where the borders sit. Routine antenatal care, early-pregnancy bleeding and miscarriage, preeclampsia, fetal movement advice and the delivery itself belong with gynecology and obstetrics, which is where those subjects are covered in full; this unit takes over the layer above them. Fertility treatment and embryo testing before pregnancy belong with IVF and reproductive health. Care of the baby after birth belongs with pediatrics and its neonatal intensive care unit, and in practice the neonatal team is involved before birth whenever a diagnosis has been made.

What a perinatologist actually does

A perinatologist is an obstetrician who has completed further sub-specialty training in maternal-fetal medicine and spends the working week on complicated pregnancies. In American usage the same doctor is called a maternal-fetal medicine specialist, or an MFM doctor; in British and European usage the same work is often called fetal medicine. The titles differ, the job does not.

Three things make up most of it. The first is ultrasound of a kind that general obstetric scanning does not attempt — detailed anatomical survey, fetal echocardiography, Doppler of several vascular territories, cervical measurement, and the interpretation that turns those images into a management plan. The second is procedures: chorionic villus sampling, amniocentesis, fetal blood sampling and transfusion, laser treatment of shared-placenta complications, drainage of fetal fluid collections. The third, and the least visible, is co-ordination — a pregnancy with a fetal cardiac diagnosis needs the paediatric cardiologist, the neonatal team, the anaesthetist and the delivery unit all working from the same plan and the same date.

A perinatologist does not usually replace the obstetrician who has been looking after the pregnancy. In most arrangements the two run in parallel: the referring obstetrician continues routine care, and the perinatologist owns the specific problem and the scan schedule that goes with it. Whether the perinatologist also performs the delivery depends on what the problem is — an abnormally invasive placenta or a fetal condition needing immediate surgery is delivered by the specialist team; a well-controlled thyroid disorder is not.

Who is referred, and why

Referrals to fetal medicine come from four directions, and it is useful to know which one applies because they lead to very different appointments.

A finding on a scan. Something has been seen — a measurement outside the expected range, a structure that did not look as expected, a marker, a fluid volume, a placental position. This is the commonest reason, and it is the one most likely to end with reassurance.

A screening result. A combined first-trimester screen or a cell-free DNA test has returned a higher-chance result, which is a probability rather than a diagnosis and is followed by a conversation before it is followed by anything else.

A maternal condition. Pre-existing diabetes, hypertension, thyroid disease, lupus or another connective tissue disease, epilepsy, congenital or acquired heart disease, kidney disease, a transplant, a clotting disorder, inflammatory bowel disease, or a medicine whose use in pregnancy needs planning. These referrals ideally happen before conception, when the greatest number of choices is still available.

The obstetric history. A previous preterm birth, a previous baby with growth restriction, preeclampsia, stillbirth, an earlier caesarean — particularly more than one — a uterine operation such as myomectomy, or recurrent loss. History-based referral is the least intuitive category for patients, because nothing is wrong yet; the point is that the plan is made before anything can be.

Maternal age belongs here too, with a correction. The phrase “geriatric pregnancy” for women over 35 has been retired, and rightly so. Pregnancy after 40 does shift the chance of chromosomal conditions and of some placental and hypertensive complications, which is why screening choices are discussed differently — but the great majority of pregnancies after 35, and a great many after 40, are entirely straightforward. Age on its own changes the conversation, not the outcome.

Previous loss, recurrent miscarriage and stillbirth

A pregnancy that follows a loss is medically different only in some respects, and emotionally different in all of them. Recurrent miscarriage — conventionally defined as the loss of consecutive early pregnancies — is investigated for a limited set of causes: antiphospholipid syndrome, uterine structural abnormalities, parental chromosomal rearrangements, thyroid dysfunction and poorly controlled diabetes. In a substantial proportion of couples no cause is identified, which is a genuinely better result than it sounds, because unexplained recurrent miscarriage carries a good chance of subsequent live birth without any treatment at all.

A pregnancy after stillbirth is managed with more surveillance than the evidence strictly demands, and the reason is honest rather than scientific: the surveillance is partly for the parents. Where the cause of the previous stillbirth was identified — growth restriction, a placental problem, a cord accident, an infection, a genetic condition — the plan targets it specifically, and delivery is usually planned rather than awaited. Where no cause was found, and that is common, the plan is generic growth and Doppler surveillance with a delivery date agreed in advance.

What perinatology cannot do here is promise a different outcome. What it can do is make sure that nothing detectable is missed, and that the decisions are made before the anxiety of the third trimester makes them harder to make well.

First-trimester screening: the NT scan and nuchal translucency

The NT scan — the nuchal translucency scan — is performed between 11 weeks and 13 weeks 6 days, and it does three separate jobs that patients often conflate. It confirms that the pregnancy is viable and dates it accurately from the crown-rump length. It establishes the number of babies and, in a twin pregnancy, the chorionicity, which is the single most important piece of information in the whole pregnancy and can only be determined reliably in this window. And it measures the nuchal translucency, the fluid layer at the back of the fetal neck, which combined with maternal age and two blood markers produces a chance figure for the common chromosomal trisomies.

Two refinements are often added at the same sitting. The nasal bone is assessed as present or absent, and the ductus venosus waveform is examined; both adjust the calculated chance and both are also relevant to fetal cardiac assessment, since an abnormal ductus venosus flow pattern at this stage is associated with cardiac defects independently of chromosomes.

A word about what this scan is not. A first trimester screening result is a probability, expressed as a chance such as one in a given number. It is not a diagnosis, it does not say the baby has or does not have a condition, and a “low chance” result is not a guarantee. The screen also performs a second function that is easy to overlook: an increased nuchal translucency with entirely normal chromosomes is itself a reason for detailed cardiac and anatomical assessment later, because it is associated with structural heart disease and with some genetic syndromes that chromosome testing does not detect.

The scan is done through the abdomen in most women; a transvaginal approach is sometimes needed for a clear view, and it is a matter of image quality rather than of anything being wrong.

NIPT and cell-free DNA testing

NIPT — non-invasive prenatal testing, also described as cell free DNA testing — analyses fragments of placental DNA circulating in the mother’s blood. A NIPT test can be taken from around ten weeks, needs only a venous sample, and screens with high accuracy for trisomy 21, 18 and 13, and where requested for the sex chromosome conditions. It has largely displaced the older serum screens where it is available and affordable.

Two properties of it are consistently misunderstood.

• It remains a screening test. A high-chance NIPT result is confirmed by an invasive test before any irreversible decision is made — never on the NIPT alone. This is not caution for its own sake: the DNA tested is placental, not fetal, and placental and fetal chromosomes are not always identical.
• Its accuracy depends on how common the condition is. The same test with the same laboratory performance produces a very different chance of being right for trisomy 21 in a 40-year-old than for a rare microdeletion in a 25-year-old. This is why a false positive nipt result is far more likely for the rare conditions on extended panels than for the common trisomies, and why extended panels are offered with more caution than the marketing around them suggests.

NIPT can also fail to give a result at all, usually because the proportion of placental DNA in the sample — the fetal fraction — is too low. This happens more often in early gestation and at higher maternal weight. A repeat sample usually resolves it. A persistently low fetal fraction is itself worth a conversation rather than simply another tube.

The quad screen

Where NIPT is not available, the quad screen — a second-trimester blood test measuring four maternal serum markers — remains a valid alternative, with lower detection and a higher false-positive rate than cell-free DNA. It retains one advantage: its markers also flag some open neural tube defects and a subset of placental problems, which cell-free DNA does not look at.

Neither test looks at structure. A baby can have a normal NIPT result and a significant structural anomaly, which is the whole reason the anomaly scan still happens.

The anomaly scan (the 20 week scan)

The anomaly scan — the 20 week scan, also called the mid-trimester or detailed scan — is performed between roughly 18 and 22 weeks and is a systematic anatomical survey of the baby from head to feet. It is the single most informative examination of the pregnancy. It examines the brain and skull, face and lips, spine, chest and lungs, the heart in several planes, the abdominal wall and internal organs, the kidneys and bladder, and the limbs, and it assesses the placenta, the cord and the amniotic fluid volume.

What it finds, it finds well; what it cannot see, it cannot see, and that boundary matters. Detection depends heavily on the organ system — some anomalies are almost always identified, others are difficult or impossible before birth, and some conditions do not develop until the third trimester or later. Image quality is also a real constraint: maternal body habitus, fetal position, scar tissue from previous surgery and reduced amniotic fluid all limit what can be seen, and a scan reported as technically limited is a statement about the images, not about the baby.

A normal anomaly scan is genuine reassurance about structure. It is not a guarantee of a healthy baby, because it says nothing about most genetic conditions, nothing about metabolic disease, and little about how the placenta will perform in the third trimester.

4D ultrasound

4D ultrasound deserves an honest description. The 3D and 4D surface-rendering modes produce the recognisable face images that many parents want, and they have a limited clinical role — they are genuinely useful for facial clefts, for some skeletal and neural tube abnormalities, and occasionally for showing parents a finding in a way that a cross-sectional image cannot. They add nothing to the diagnostic quality of the anomaly scan itself, which is performed in two dimensions. A 4D session sold as a keepsake is not a medical examination and should not be mistaken for one.

Soft markers: the findings that usually mean nothing

Soft markers are minor ultrasound findings that are not abnormalities in themselves, but occur slightly more often in babies with chromosomal conditions. They are the most common reason for a frightened referral to fetal medicine, and in the overwhelming majority of cases the outcome of that referral is reassurance.

The interpretation changed substantially once cell-free DNA testing became widely used. An isolated soft marker in a pregnancy with a low-chance NIPT result adds very little, and current practice is to stop escalating on that basis alone. An isolated marker where no screening has been done is a reason to offer screening, not to offer an invasive test. Two or more markers together, or a marker alongside a structural finding, is a different conversation.

Echogenic intracardiac focus

An echogenic intracardiac focus is a small bright spot in the fetal heart, usually in the left ventricle, caused by mineralisation within a papillary muscle. It is not a heart defect, it does not affect how the heart works, it does not need follow-up in itself, and it disappears in most cases. It is found in a meaningful proportion of entirely normal pregnancies, and more often in some populations than others. As an isolated finding with normal screening it is of no clinical significance.

Choroid plexus cyst

A choroid plexus cyst is a small fluid-filled space within the choroid plexus, the structure in the brain’s ventricles that produces cerebrospinal fluid. It is not a brain abnormality and has no effect on brain development or intelligence. The great majority resolve by the third trimester. Their only clinical relevance is a weak association with trisomy 18 — but trisomy 18 almost always produces multiple other abnormalities that the same scan would show, so an isolated cyst with an otherwise normal anatomical survey is not pursued.

Pyelectasis

Pyelectasis — mild dilatation of the renal pelvis, the collecting area where urine leaves the kidney — is measured in millimetres and graded by gestational age. Mild pyelectasis is common, is more frequent in male fetuses, and resolves before or shortly after birth in most cases. It is followed with a repeat scan in the third trimester rather than investigated immediately. Where dilatation is more marked or progresses, it is followed after birth, because a proportion of these babies have an underlying obstruction or reflux that benefits from being known about early. This is the one soft marker with a genuine postnatal action attached to it.

Invasive testing: CVS and amniocentesis

Screening estimates a chance. Only an invasive test, which samples fetal or placental tissue directly, gives a diagnosis. Two procedures do this, and the choice between them is almost entirely a matter of gestational age.

Chorionic villus sampling

Chorionic villus sampling — CVS — takes a small sample of placental tissue from about 11 weeks onwards, through the abdomen with a needle or through the cervix with a fine catheter, in both cases under continuous ultrasound guidance. Its advantage is timing: a diagnosis in the first trimester rather than the middle of the second, which matters both for the decisions that follow and for how long the uncertainty lasts.

Its limitation is biological. The tissue sampled is placental, so CVS shares NIPT’s underlying problem in a smaller form: confined placental mosaicism, where the placenta carries a chromosomal abnormality the baby does not. This is uncommon but it is the reason an unexpected CVS result is sometimes followed by amniocentesis rather than acted on. CVS also cannot measure amniotic fluid alpha-fetoprotein, so it does not contribute to detecting open neural tube defects.

Amniocentesis

Amniocentesis is performed from 15 weeks and withdraws a small volume of amniotic fluid, which contains cells shed by the baby, through a fine needle passed through the abdominal wall under ultrasound guidance. It is the reference standard for fetal chromosomal and genetic diagnosis. The fluid can also be tested for infection and, where relevant, for the metabolic and enzyme assays that some inherited conditions require.

Both procedures carry a small risk of pregnancy loss related to the procedure itself. Two honest points about that number. Modern estimates from experienced centres are considerably lower than the figures quoted in older patient information, which are still widely repeated. And the risk is strongly operator- and volume-dependent, which is why the meaningful question to ask is not what the published figure is but what the audited figure is for the person holding the needle. Anti-D is given afterwards where the mother is rhesus negative.

Chromosomal microarray and exome sequencing

What comes back, and when, depends on what was asked for. A rapid test for the common trisomies reports within a few working days. A full karyotype requires the cells to be cultured and takes substantially longer. Chromosomal microarray examines the genome at much finer resolution than a karyotype and detects small deletions and duplications that a karyotype cannot see; it is increasingly the default where a structural anomaly has been found. Exome sequencing is reserved for specific situations, usually multiple anomalies with normal microarray, and is arranged through medical genetics.

Finer resolution brings a problem with it. Microarray and sequencing both return findings of uncertain meaning — a variant that may be significant, may be harmless, and cannot currently be classified either way. Deciding in advance how much uncertainty you want reported is part of consenting to the test, and it is a conversation better had before the sample is taken than after.

Fetal echocardiography and advanced imaging

Congenital heart disease is the most common category of major structural anomaly and the one most often missed on routine scanning, which is why it has its own examination.

Fetal echocardiography

Fetal echocardiography — a fetal echo — is a dedicated ultrasound examination of the fetal heart, performed by a fetal cardiologist or a perinatologist with specific training, usually between 18 and 24 weeks and repeated later where indicated. It assesses the four chambers, both outflow tracts, the great vessels and the venous connections, and uses colour and pulsed Doppler to demonstrate flow and rhythm. It is a longer and more detailed examination than the cardiac component of the anomaly scan.

It is offered when there is a reason: a suspected abnormality on the anomaly scan, an increased nuchal translucency or abnormal ductus venosus flow earlier in the pregnancy, a family history of congenital heart defect in a parent or previous child, maternal pre-gestational diabetes, certain maternal medicines, some maternal autoimmune antibodies that can affect fetal cardiac conduction, a monochorionic twin pregnancy, or an irregular fetal heart rhythm noticed at any visit.

What prenatal diagnosis changes is not the defect but the birth. A duct-dependent circulation identified before delivery means the baby is born in a hospital with paediatric (pediatric) cardiac surgery on site, with the medicine that keeps the duct open ready in the room rather than being started after collapse at home. That single logistical difference is the main reason fetal echocardiography exists.

Its limits should be stated plainly. Some defects — coarctation of the aorta is the classic example — are genuinely difficult to exclude before birth. Some abnormalities evolve during pregnancy and are not present at the time of the scan. And the fetal circulation is not the newborn circulation: a heart that copes perfectly in the womb may decompensate in the first days of life, which is why a prenatal diagnosis is followed by a postnatal one.

Fetal MRI

Fetal MRI is a problem-solving examination, not a screening one. It is used almost always after ultrasound has found something, and most often for the fetal brain, where it adds detail about cortical development, the posterior fossa and haemorrhage (hemorrhage) that ultrasound cannot match, particularly late in pregnancy when the skull limits the acoustic window. It is also used for lung volume assessment in diaphragmatic hernia, for complex neck and chest masses that will affect the airway at delivery, and for placental invasion.

It uses no ionising radiation and no contrast agent in pregnancy. It is performed without sedation, takes considerably longer than a scan, and requires the mother to lie still in a confined space, which is the practical constraint that matters most. Its result changes management in a meaningful minority of cases — usually by refining a diagnosis ultrasound had already suggested, occasionally by overturning it.

Fetal growth restriction (IUGR)

Fetal growth restriction means a baby that has not achieved its own growth potential, usually because the placenta is not delivering enough. IUGR — intrauterine growth restriction — is the older term for the same thing and is still in wide use. It is one of the most important conditions in obstetrics, because it is the single largest identifiable contributor to stillbirth in otherwise normal babies, and because detecting it changes what happens.

The distinction that matters most is between growth restriction and a constitutionally small baby. Small for gestational age describes a baby below a size threshold for its gestation — often the tenth centile — which may simply reflect small parents. Growth restriction describes a baby whose growth has faltered, whatever centile it currently sits on. A baby on the fortieth centile that was on the eightieth two months ago is growth restricted; a baby that has tracked the fifth centile throughout may be entirely well. This is why serial measurement beats any single one.

The growth scan and estimated fetal weight

A growth scan measures the fetal head circumference, abdominal circumference and femur length, and from them calculates an estimated fetal weight which is plotted on a centile chart. Two properties of that number are worth knowing before it causes unnecessary alarm. It is an estimate with a genuine margin of error in either direction, which widens as the baby gets bigger — a specific figure in grams conveys a precision the method does not have. And because of that error, scans are not repeated at short intervals; a fortnight or more between them is standard, because measuring more often mostly measures the error.

The abdominal circumference is the most informative single measurement, because the fetal liver shrinks first when nutrient supply falls, and a flattening abdominal circumference is often the earliest sign.

Doppler studies: umbilical artery Doppler and the fetal circulations

Doppler ultrasound measures the resistance the blood meets in a vessel, and it is what separates a small baby that is coping from a small baby that is not.

• Umbilical artery Doppler assesses the placental circulation. Rising resistance, then absent and then reversed flow in the diastolic phase, marks a deteriorating placenta, and this sequence is the backbone of surveillance in early-onset growth restriction. It is the one Doppler measurement shown to reduce perinatal death when used in high-risk pregnancies.
• Middle cerebral artery Doppler shows the fetal response. Falling resistance in the brain’s circulation indicates that blood is being preferentially redirected there — brain sparing — which is a sign of adaptation to a limited supply rather than a sign of safety. The ratio between the cerebral and umbilical values is more sensitive than either alone and is the main tool in late-onset growth restriction, where umbilical Doppler often stays normal.
• Ductus venosus Doppler assesses the fetal heart’s tolerance of the situation. Abnormal waveforms here indicate cardiac decompensation and are a late finding; in very preterm growth restriction they are a principal trigger for delivery.
• Uterine artery Doppler is done earlier, in the second trimester, and predicts rather than monitors: raised resistance identifies pregnancies at higher risk of preeclampsia and growth restriction, and selects who needs the extra surveillance.

Treatment for established growth restriction does not exist. No drug, diet, supplement or period of bed rest has been shown to make a failing placenta work better. The entire management is surveillance and timing: watching closely enough to know when the risk of staying in exceeds the risk of coming out, and delivering at that point. Where that point falls very preterm, corticosteroids are given beforehand to mature the lungs, and magnesium sulphate for fetal neuroprotection. Prevention is a different matter: in women identified as high risk early, low-dose aspirin started in the first trimester reduces the incidence of both preeclampsia and growth restriction — a decision made with the doctor who knows the full history, since it is not appropriate for everyone.

Amniotic fluid: too little and too much

Amniotic fluid in the second half of pregnancy is essentially fetal urine, and its volume is therefore a live readout of fetal kidney function and placental perfusion. It is measured either as the amniotic fluid index, the sum of the deepest pockets in four quadrants of the uterus, or as the single deepest vertical pocket. Both are in use; the single-pocket method identifies fewer cases and leads to fewer inductions without a worse outcome, which is a point in its favour.

Oligohydramnios

Oligohydramnios is too little amniotic fluid — conventionally an amniotic fluid index below 5 cm or a deepest pocket below 2 cm. It matters for two different reasons depending on when it appears. In the second trimester it points to a cause: ruptured membranes, a fetal urinary tract obstruction, absent or non-functioning kidneys, or severe early placental failure. Prolonged severe oligohydramnios in the mid-trimester also impairs lung development, because the fetal lungs need fluid to expand into, and that consequence can be more serious than the original cause.

Near term the significance is different and usually simpler: it is most often a marker of a placenta running out of reserve, and it is one of the standard triggers for delivering rather than continuing. Maternal dehydration lowers the volume measurably, so a borderline result is often rechecked after fluids before anything is decided.

Polyhydramnios

Polyhydramnios is too much fluid — conventionally an amniotic fluid index above 24 cm or a deepest pocket above 8 cm. In a majority of mild cases no cause is ever found and the pregnancy is normal. The investigation looks for the causes that do exist: maternal diabetes, which is the most common identifiable one; anything that stops the baby swallowing, from an oesophageal (esophageal) or duodenal atresia to a neuromuscular condition; fetal anaemia; some infections; and, in twins, twin-to-twin transfusion syndrome. A detailed scan and a glucose test are the usual first steps.

Marked polyhydramnios carries its own mechanical problems independent of the cause: an overdistended uterus is associated with preterm labour, with the cord prolapsing when the membranes rupture because the presenting part is not engaged, with unstable lie, and with bleeding after birth from a uterus that struggles to contract down. Where the volume causes maternal breathlessness, drainage by amnioreduction can relieve it, accepting that fluid usually reaccumulates.

Where the placenta sits — and why it usually stops mattering

Placental position is reported on every anomaly scan and is one of the largest single sources of unnecessary worry in pregnancy, because two of the three things reported are almost always benign.

Anterior placenta

An anterior placenta means the placenta has implanted on the front wall of the uterus, between the baby and the abdominal wall. It is one of the normal positions — roughly as common as a posterior placenta — and it is not a complication, not a risk factor and not a reason for extra scans. Nothing about the pregnancy, the birth or the baby is changed by it.

What it does change is what the mother experiences. The placenta lies between the baby and the abdominal wall, so fetal movements are felt later and more faintly, particularly in a first pregnancy; a woman with an anterior placenta may not feel definite movements until several weeks after a friend with a posterior one. Doppler heart-rate monitoring can take longer to find the heartbeat, and the scan images are sometimes less crisp. None of this indicates a problem, and none of it alters the standard advice about monitoring movements once a pattern is established — which is covered with obstetrics, where fetal movement is dealt with in full. A caesarean (cesarean) with an anterior placenta is technically slightly different for the surgeon and identical for the patient.

Low-lying placenta and placenta previa

A low lying placenta at the anomaly scan means the placental edge is close to, but not covering, the internal cervical os. Placenta previa means it covers it. The distinction is measured in millimetres and both are reported far more often at 20 weeks than they exist at term, for a reason that is purely geometrical: the lower uterine segment forms and lengthens through the third trimester, and the placenta is carried upwards away from the cervix as it does. The great majority of low-lying placentas at 20 weeks are nowhere near the cervix by 32 to 36 weeks, which is why the finding is followed by a repeat scan rather than by a plan.

Where it persists, the plan is straightforward and firm. A placenta covering or very close to the cervix means delivery by planned caesarean, because the placenta is in front of the exit and labour would tear it. It also means that bleeding in the second half of pregnancy is assessed in hospital rather than at home, and that vaginal examination is avoided outside a setting equipped to deal with haemorrhage (hemorrhage). Persistent previa is one of the situations where the delivery date is set in advance rather than awaited, and where blood is cross-matched before the operation starts.

Velamentous cord insertion and vasa previa

Velamentous cord insertion means the umbilical cord does not insert into the body of the placenta but into the membranes beside it, so the vessels run unprotected across the membranes for some distance before reaching the placental disc. Without Wharton’s jelly around them, those vessels can be compressed, and they can tear. It is found in a small percentage of singleton pregnancies and considerably more often in twins, and it is associated with growth restriction, so it earns serial growth surveillance.

Its serious form is vasa previa, where those unprotected vessels cross the cervix ahead of the presenting part. If the membranes rupture there, the bleeding is fetal, and fetal blood volume is very small. This is one of the few conditions in obstetrics where prenatal diagnosis is the whole difference between a routine outcome and a catastrophic one: identified in advance, it is managed by planned caesarean before labour begins, and outcomes are good. It is looked for specifically with transvaginal ultrasound and colour Doppler in the situations that predispose to it — velamentous insertion, a bilobed or succenturiate placenta, a low-lying placenta earlier in pregnancy, and IVF conception.

Placenta accreta spectrum

Placenta accreta describes a placenta that has implanted abnormally deeply into the uterine wall and will not separate after birth. The condition is graded by depth, and the modern term for the whole group is the placenta accreta spectrum: accreta where the placenta adheres to the myometrium, placenta increta where it invades into it, and placenta percreta where it penetrates through the uterine wall and can involve the bladder or other pelvic structures.

This is the most serious placental condition in obstetrics, and it is also the one where prenatal diagnosis changes the outcome most dramatically. Undiagnosed, it presents as torrential haemorrhage during an otherwise ordinary caesarean, when the placenta is found not to separate. Diagnosed in advance, it becomes a planned operation, at a planned gestation, in a hospital with a blood bank and interventional radiology, performed by a team that has assembled for it: an experienced obstetric surgeon, urology on standby because the bladder is frequently involved in percreta, anaesthesia (anesthesia) prepared for major transfusion, and a neonatal team for a baby delivered before term.

Why this region sees more of it

Placenta accreta spectrum is not evenly distributed, and the reason is entirely mechanical. It requires a defect in the uterine lining for the placenta to invade through, and by far the most common such defect is a caesarean scar. The risk rises with each previous caesarean delivery, and it rises steeply when a placenta previa in this pregnancy is sitting over a previous scar — that combination is the single highest-risk situation in the field. Other uterine surgery contributes: myomectomy, repeated curettage, endometrial ablation, and treatment of intrauterine adhesions.

Turkey and the surrounding region have had high caesarean delivery rates for a sustained period, and the consequence arrives one generation later in exactly this form. A unit here sees more accreta spectrum than a unit in a country with a lower caesarean rate, and it sees it in women who did not have a difficult first pregnancy — the first caesarean is often the least eventful part of the story. This is one of the few situations where a regional caseload is a genuine clinical advantage rather than a marketing line: the condition is rare enough elsewhere that many obstetricians will manage a handful in a career.

How it is diagnosed and managed

Diagnosis is by ultrasound in the first instance, in a woman whose history has already put her in the risk group — which is why the history is asked about at booking rather than discovered in theatre. The features looked for are loss of the normal clear zone between placenta and myometrium, irregular vascular lacunae within the placenta, thinning of the myometrium, bulging of the uterine contour, and abnormal vascularity at the bladder interface on colour Doppler. MRI is added where ultrasound is equivocal, where the placenta is posterior, or to define the extent of invasion before surgery.

Management is planned delivery before labour starts, at a gestation chosen to balance prematurity against the chance of bleeding — earlier than term, and earlier again where there has been bleeding. In most cases the operation is a caesarean hysterectomy with the placenta left in place, because attempting to remove a placenta that has invaded the wall is what causes the haemorrhage. Uterus-preserving approaches exist and are used selectively, in carefully chosen cases, with the clear understanding that they carry a risk of later bleeding and further surgery. That trade-off is discussed before the date is set, not on the day.

Twins and higher-order pregnancies

Multiple pregnancy is not simply a pregnancy with more babies in it. The complication rates are higher for essentially everything — preterm birth, growth restriction, preeclampsia, gestational diabetes, bleeding after delivery — and one variable governs the whole management plan.

Chorionicity: dichorionic, monochorionic twins and monoamniotic twins

Chorionicity describes how many placentas there are, and it is not the same question as whether the twins are identical. Dichorionic twins have a placenta each, whether or not they are genetically identical. Monochorionic twins share one placenta, and within it their circulations are connected by vascular anastomoses — which is the source of every complication unique to twins. Monoamniotic twins share both the placenta and a single amniotic sac, with no membrane between them, and additionally face the risk of cord entanglement.

Chorionicity is determined most reliably in the first trimester, by the shape of the membrane where it meets the placenta — the lambda sign for dichorionic, the T sign for monochorionic — and it becomes progressively harder to establish as pregnancy advances. This is the strongest argument for an early scan in a twin pregnancy: a chorionicity determined at 12 weeks sets a surveillance schedule for the following six months, and one guessed at 24 weeks may set the wrong one.

The practical consequence is scan frequency. A dichorionic twin pregnancy is scanned regularly for growth. A monochorionic one is scanned fortnightly from the middle of the second trimester, and those scans are looking for specific things — fluid discordance, bladder visibility, Doppler changes — not simply measuring the babies.

Selective fetal growth restriction

Selective fetal growth restriction is significant growth discordance between twins, most often because the shared placenta is divided unequally between them. It is classified by the umbilical artery Doppler pattern in the smaller twin, and that classification determines the outlook and the management, because intermittently absent or reversed flow behaves quite differently from persistently abnormal flow. The difficulty is unique to monochorionic pairs: because the circulations are connected, deterioration in one twin can affect the other, and decisions that would be straightforward in a singleton — deliver the compromised baby — mean delivering a healthy twin prematurely as well.

Twin-to-twin transfusion syndrome

Twin to twin transfusion syndrome occurs in monochorionic pregnancies when the vascular connections in the shared placenta carry blood disproportionately from one twin to the other. The donor twin becomes underfilled — producing little urine, with a small or invisible bladder and progressively less amniotic fluid until it is shrink-wrapped against the uterine wall. The recipient becomes overloaded — passing large volumes of urine, with a distended bladder, excess fluid, and a heart working against a volume it cannot handle. Untreated severe disease has a very poor outlook for both.

It is a disease of the placenta, not of the babies. Neither twin is abnormal; the vascular architecture between them is.

TTTS stages

The ttts stages in general use run from I to V and describe progression: fluid discordance alone; then a donor bladder that can no longer be seen; then abnormal Doppler findings; then hydrops in the recipient; then the death of one or both twins. Staging drives management, because stage I frequently remains stable and is often watched, while more advanced disease is treated.

Fetoscopic laser treatment

The definitive treatment is fetoscopic laser photocoagulation. A fine endoscope is passed through the abdominal wall into the recipient’s amniotic sac under ultrasound guidance and local anaesthesia (anesthesia), the vascular equator of the shared placenta is mapped, and the connecting vessels are coagulated with a laser — separating the two circulations so that each twin is supplied by its own territory. Excess fluid is drained at the end of the procedure. Fetoscopy of this kind is the clearest example of fetal therapy that alters the natural history of a disease rather than simply monitoring it, and it is performed in a small number of centres because it depends on volume.

It is not without cost. Preterm rupture of the membranes and preterm birth are the main complications, and the procedure cannot always be completed — an anterior placenta, in this one specific context, genuinely does make the operation harder. Where laser is not feasible, amnioreduction relieves the pressure without treating the cause. After treatment, surveillance continues for recurrence and for the reverse condition, twin anaemia polycythemia sequence.

Twin anaemia polycythaemia sequence (twin anemia polycythemia sequence)

Twin anemia polycythemia sequence — TAPS — is a chronic, slow transfusion through a few tiny residual connections, producing a marked difference in haemoglobin (hemoglobin) between the twins without the fluid discordance that defines twin-to-twin transfusion. Because the amniotic fluid volumes look normal, it is invisible to a scan that only measures fluid, and it is detected by middle cerebral artery Doppler — high peak systolic velocity in the anaemic twin, low in the polycythaemic one. It occurs spontaneously and after laser treatment, which is why Doppler surveillance continues in monochorionic pregnancies whether or not they have been treated.

Cervical length and preterm birth

Preterm birth is the largest single cause of death and long-term disability in babies without an anomaly, and most of it is not predicted by anything in the history — a majority of preterm births happen to women having their first baby, with no risk factors at all. That is what makes measurement useful.

Measuring the cervix: what a short cervix means

Cervical length is measured by transvaginal ultrasound, which is the only reliable way; an abdominal scan cannot see the cervix well enough and systematically overestimates. The measurement is taken in the second trimester, most usefully around the time of the anomaly scan, and a length of 25 mm or less is the threshold in general use for a short cervix. The shorter the measurement and the earlier it is found, the higher the risk. Funnelling — dilatation of the internal os with the membranes descending into it — adds information but the length is the primary number.

A short cervix is a risk marker, not a diagnosis of anything, and most women with one do not deliver preterm. It identifies who benefits from treatment, which is its entire purpose.

Progesterone for short cervix

Progesterone for short cervix, given vaginally from the second trimester until around 36 weeks, reduces preterm birth in women found to have a short cervix, including those with no previous preterm delivery. It is the least invasive of the available options and the one with the broadest evidence in this specific group. The prescribing decision, the preparation and the timing belong with the doctor managing the pregnancy — that is not something to start or stop on the basis of a web page.

Cervical cerclage

Cervical cerclage is a suture placed around the cervix to reinforce it, inserted vaginally under regional or general anaesthesia (anesthesia) as a day procedure and removed at around 36 to 37 weeks, or earlier if labour starts. It is used in three distinct situations, and conflating them is the commonest source of confusion.

• History-indicated — placed in the early second trimester on the basis of previous mid-trimester losses or preterm births with a clinical picture of cervical insufficiency, before any measurement in this pregnancy.
• Ultrasound-indicated — placed when the cervix shortens in a woman with a relevant history, which is why she is being scanned serially in the first place.
• Rescue cerclage — placed when the cervix is already dilated and the membranes are visible or bulging. Rescue cerclage is an attempt to buy gestational weeks in a situation that would otherwise proceed to loss, and it is discussed frankly, because it succeeds in some cases and not in others and carries a risk of rupturing the membranes during the attempt.

Where a vaginal approach has already failed or the cervix is too short to suture — after a trachelectomy for cervical cancer, for instance — a transabdominal cerclage can be placed, increasingly by laparoscopy and ideally before conception. It commits the woman to caesarean delivery.

Cerclage and progesterone are not competitors for the same patient; they answer different clinical pictures, and a cervical pessary is a third option used in some centres. What none of them does is treat established preterm labor. Once labour is genuinely underway, the interventions that improve outcomes act on the baby rather than the uterus: antenatal corticosteroids to mature the lungs, magnesium sulphate for neuroprotection before 32 weeks, and birth in a hospital with neonatal intensive care on site, since transferring a baby after birth is worse than transferring the mother before it. Drugs that suppress contractions buy time for those things to happen; they do not prolong pregnancy meaningfully on their own.

Fetal anaemia (fetal anemia) and intrauterine transfusion

Fetal anemia is one of the few fetal conditions with a direct, effective treatment before birth — and the story of how it became one is the origin of fetal medicine as a specialty.

Rhesus disease and red cell alloimmunisation

Rh incompatibility arises when a rhesus-negative mother is exposed to rhesus-positive fetal red cells and produces antibodies against them. The antibodies cross the placenta and destroy fetal red cells, producing fetal anemia that can progress to heart failure and hydrops. Routine anti-D prophylaxis has made this uncommon where it is available, and antibodies other than anti-D — anti-Kell in particular, which suppresses red cell production as well as destroying cells — now account for a substantial share of severe cases. Non-invasive determination of the fetal rhesus type from maternal blood makes it possible to tell early whether an at-risk pregnancy is at risk at all.

Other causes of fetal anaemia are looked for where no antibody is found: parvovirus B19 infection, which suppresses fetal red cell production and often resolves after a single transfusion; fetomaternal haemorrhage (hemorrhage); some inherited haemoglobin disorders; and, in monochorionic twins, twin anaemia polycythaemia sequence.

Detecting fetal anemia without a needle

Fetal anaemia used to be assessed by repeated amniocentesis. It is now detected by measuring the peak systolic velocity in the fetal middle cerebral artery: anaemic blood is thinner and moves faster, and the velocity rises predictably as haemoglobin falls. This single measurement replaced serial invasive testing and is one of the clearest examples in obstetrics of a non-invasive test displacing an invasive one outright.

Intrauterine transfusion

Intrauterine transfusion delivers donor red cells directly into the fetal circulation, usually into the umbilical vein at the point where the cord inserts into the placenta, through a needle passed under continuous ultrasound guidance. The fetal haemoglobin is measured at the start, the volume calculated, and the transfusion given over several minutes; procedures are repeated at intervals until the baby is mature enough to be delivered. In experienced hands it is highly effective, and babies who would once have died or been born with severe brain injury are now born well.

Hydrops fetalis

Hydrops fetalis — abnormal fluid accumulation in two or more fetal compartments — is the end stage of severe fetal anaemia and also of many other conditions: cardiac abnormalities and arrhythmias, chromosomal and genetic syndromes, infections, chest masses, and metabolic disease. The distinction that governs everything is between immune hydrops, from red cell antibodies, and non-immune hydrops, which is now the large majority. Immune hydrops is treatable by transfusion. Non-immune hydrops is treatable only where its specific cause is, and in a significant proportion of cases it is not — which is one of the conversations in this specialty where the honest answer is the difficult one.

Structural anomalies and fetal surgery

When the anomaly scan finds something structural, the questions that follow are always the same four: is it isolated or part of a syndrome, is it survivable, is it treatable, and where should the baby be born. Genetic testing usually answers the first, a detailed re-scan and often a fetal MRI the second and third, and the answer to the fourth is what most changes the outcome.

Gastroschisis and omphalocele

Gastroschisis is a defect in the abdominal wall, characteristically to the right of the cord, through which bowel protrudes into the amniotic fluid with no covering membrane. It is usually isolated — not associated with chromosomal conditions — and is more common in very young mothers. The bowel is what determines the outcome: exposure to amniotic fluid inflames and thickens it, and the postnatal course depends on how well it works afterwards. These pregnancies are followed with serial growth scans, because growth restriction is common, and delivered in a hospital with paediatric (pediatric) surgery, where the abdominal wall is closed either immediately or in stages.

Omphalocele — exomphalos — is a midline defect where abdominal contents herniate into the base of the cord, covered by a membrane, with the cord inserting into the sac. The distinction from gastroschisis matters enormously, because omphalocele is frequently not isolated: it is associated with chromosomal conditions, with cardiac abnormalities, and with syndromes including Beckwith-Wiedemann. The finding therefore triggers a full genetic workup and fetal echocardiography, and the prognosis depends far more on what else is found than on the defect itself. A large omphalocele containing liver behaves differently from a small one containing only bowel.

Congenital diaphragmatic hernia

Congenital diaphragmatic hernia is a defect in the diaphragm through which abdominal organs move into the chest, compressing the developing lung. The problem after birth is not the hole — that is repaired — but the lungs, which have had no room to develop and carry abnormal pulmonary vasculature. Prognosis is estimated before birth from the lung-to-head ratio and from lung volumes on MRI, and from whether the liver has moved up into the chest. Delivery in a centre with neonatal intensive care and paediatric surgery is essential, and in selected severe cases fetoscopic tracheal occlusion — temporarily blocking the fetal trachea so lung fluid accumulates and stimulates growth — is offered in specialist centres as part of ongoing evaluation.

Spina bifida and neural tube defects

Spina bifida is a failure of the neural tube to close, leaving the spinal cord and its coverings exposed. It is usually identified at the anomaly scan, both directly and by the characteristic changes it produces in the fetal skull and posterior fossa. The level of the lesion is the main determinant of leg function and continence, and hydrocephalus is common. Folic acid before conception and in early pregnancy substantially reduces the incidence, which is the single most effective preventive measure in this whole field.

Fetal surgery for open spina bifida — repairing the defect before birth, by open hysterotomy or fetoscopically — is established in a small number of centres worldwide. It reduces the need for shunting and improves motor function compared with repair after birth, at the cost of a higher risk of preterm delivery and of uterine complications affecting future pregnancies. Eligibility is narrow and defined by strict criteria. It is mentioned here because families ask about it and deserve an accurate account: it is a real option for a small, specific group, evaluated at a fetal surgery centre, not a general alternative to postnatal repair.

Pregnancy with a medical condition

Maternal medicine is half of maternal-fetal medicine and the half that gets less attention. The principle running through all of it is that a well-controlled condition managed by people who know the pregnancy version of it produces good outcomes, and that stopping treatment out of fear is usually the more dangerous choice. Nothing in this section is a reason to change any medicine — the doctor who prescribed it decides that, together with the team looking after the pregnancy, and ideally before conception.

Thyroid disease

Thyroid in pregnancy behaves differently because pregnancy itself changes thyroid physiology: requirements rise early, and the reference ranges used outside pregnancy do not apply. Untreated or undertreated hypothyroidism matters for fetal neurodevelopment in the first trimester, before the fetal thyroid is working, so the dose is usually reviewed as soon as pregnancy is confirmed rather than at the first antenatal visit. Hyperthyroidism has its own considerations, including which antithyroid drug is preferred in which trimester and the fact that the antibodies in Graves’ disease cross the placenta and can affect the fetal thyroid — which is why the fetal heart rate and growth are watched in women with high antibody levels, even those whose own thyroid has been treated definitively.

Lupus and pregnancy: antiphospholipid syndrome

Lupus and pregnancy is one of the clearest cases for pre-conception planning. Outcomes are substantially better when conception occurs during a period of stable disease, and worse when the disease is active or when there is significant kidney involvement. Some of the drugs used in lupus are not suitable in pregnancy and others are; hydroxychloroquine is generally continued, and stopping it is associated with flares. Antiphospholipid antibodies raise the risk of thrombosis, of early and late loss, of preeclampsia and of growth restriction, and are managed with a defined antithrombotic plan agreed in advance. Anti-Ro and anti-La antibodies can affect the fetal cardiac conduction system, which is why women carrying them have fetal cardiac surveillance in the mid-trimester. This work is done jointly with rheumatology.

Diabetes and weight

Pre-existing type 1 and type 2 diabetes are a different clinical problem from gestational diabetes, and the difference is timing: pre-existing diabetes is present during organ formation, which is why glycaemic control before conception affects the malformation rate and why folic acid and a pre-pregnancy review matter so much. Both types bring accelerated fetal growth, polyhydramnios, and decisions about the timing and mode of delivery, and both involve fetal echocardiography. Gestational diabetes, which appears later, is managed principally by the obstetric team with endocrinology and dietetics.

Obesity in pregnancy is worth a plain, non-judgemental statement because it is often handled badly. It raises the risk of gestational diabetes, hypertensive disease, thromboembolism and caesarean delivery, and it degrades ultrasound image quality, which is a practical problem rather than a moral one — it means anomaly detection is lower and scans may need repeating. Care is adjusted for that reality: more time allocated for scanning, and a delivery plan made in advance.

Cardiac and kidney disease

Pregnancy increases cardiac output and blood volume substantially, and a heart that manages ordinary life may not manage that. Women with congenital heart disease, cardiomyopathy or significant valve disease need an assessment of how well they will tolerate pregnancy before it starts, done jointly with cardiology; a small number of conditions carry a high enough maternal risk that pregnancy is advised against, and that conversation is had honestly rather than avoided. Chronic kidney disease raises the risk of preeclampsia and growth restriction in proportion to how impaired function is, and is managed with nephrology. Women with a kidney transplant can and do have successful pregnancies, planned around graft stability and immunosuppression that is compatible with pregnancy — see organ transplantation.

Cholestasis of pregnancy

Intrahepatic cholestasis of pregnancy is a liver condition specific to pregnancy in which bile acids accumulate in the maternal circulation. It usually appears in the third trimester and its dominant symptom is itching without a rash, characteristically on the palms and soles and characteristically worse at night. The itch can be severe enough to prevent sleep, and it is frequently dismissed as a normal pregnancy nuisance for weeks before anyone measures anything.

Intrahepatic cholestasis of pregnancy is diagnosed by measuring serum bile acids, with liver enzymes, and by excluding the other causes of abnormal liver tests in pregnancy — viral hepatitis, gallstone disease, autoimmune liver disease and preeclampsia. Skin examination matters mainly to confirm there is no primary rash; the excoriations from scratching are secondary.

It matters because of the fetal risk rather than the maternal one. The condition is associated with preterm birth, meconium-stained fluid, and — at high bile acid concentrations — with stillbirth, and the association strengthens sharply in the severe range rather than rising evenly across it. That relationship is why management is built around bile acid measurement rather than around how bad the itching is: the two do not track each other, and a woman with tolerable symptoms can have concerning levels.

Management has two parts. Symptomatic treatment reduces the itch; ursodeoxycholic acid is widely used and improves biochemistry and symptoms, though the evidence that it reduces stillbirth is not established, and that is stated honestly rather than implied otherwise. The substantive intervention is timing of delivery, planned according to bile acid levels and gestation, with more surveillance in the interval. The condition resolves after birth, recurs in a majority of subsequent pregnancies, and is associated with a higher lifetime risk of hepatobiliary disease, which is worth knowing years later.

Fetal surveillance in the third trimester

Surveillance answers one question: is this baby better off inside or outside. No single test answers it, and the tests in use are better at reassurance than at prediction — a reassuring result is reliable in the short term, while an abnormal one usually prompts another test rather than an immediate decision.

The nonstress test

A nonstress test — cardiotocography, CTG — records the fetal heart rate against uterine activity for twenty minutes or more using two abdominal transducers. What it looks for is variability in the baseline rate and accelerations with movement, both of which indicate an intact and well-oxygenated nervous system. A test showing them is described as reactive.

Its limitation is the mirror image of its strength. A reactive test is strongly reassuring about the next short period; a non-reactive one most often means the baby is asleep. Fetal sleep cycles last long enough to produce a flat trace in a completely well baby, so a non-reactive test leads to a longer recording or a different test rather than to a decision. Interpretation also depends on gestation — accelerations are smaller and less frequent in a preterm baby, and applying term criteria to a 28-week trace produces false alarm.

The biophysical profile

The biophysical profile combines the nonstress test with four ultrasound observations — fetal breathing movements, gross body movement, tone, and amniotic fluid volume — each scored, giving a composite out of ten. Its logic is developmental: the brain centres controlling these behaviours mature in a known order and are lost in the reverse order as oxygenation falls, so the pattern of what is absent indicates how advanced the problem is. Amniotic fluid volume is the one component reflecting a chronic state rather than the last hour, which is why it carries disproportionate weight.

A modified profile — nonstress test plus fluid volume alone — performs nearly as well in most settings and takes a fraction of the time, which is why it is the more common version in practice.

None of this replaces what the mother notices. A change in the pattern of fetal movements is assessed the same day in maternity units everywhere, and it is assessed rather than explained away, because it is one of the few signals that arrives between appointments. Fetal movement — what is normal, how patterns change, what counting does and does not achieve — is covered in full with obstetrics.

The regional picture: consanguinity and carrier screening

Genetic risk is not distributed evenly across the world, and a fetal medicine unit in this region works with a different prior probability than one in northern Europe. Two facts shape that.

Consanguinity — marriage between relatives, most commonly first cousins — remains common across Turkey, the Middle East, North Africa and parts of South Asia. Its genetic consequence is specific and often misstated: it does not cause disease, it raises the chance that both parents carry the same rare recessive variant inherited from a shared ancestor, and therefore raises the risk of autosomal recessive conditions and of some structural anomalies. The increase in absolute risk for any individual couple is modest, and the great majority of children of consanguineous couples are healthy. What it changes is what the investigation of an anomaly should look for: in a consanguineous pregnancy with a structural finding and a normal microarray, a rare recessive syndrome moves substantially up the list, and exome sequencing is more likely to give an answer. It also makes pre-conception carrier screening genuinely worthwhile, which is arranged with medical genetics.

Haemoglobin disorders — beta-thalassaemia in particular, and sickle cell disease — are markedly more common around the Mediterranean, and Turkey has run premarital carrier screening for thalassaemia for many years in the provinces where carrier rates are highest. Where both parents are carriers, each pregnancy carries a one-in-four chance of an affected child, and prenatal diagnosis by CVS or amniocentesis is available and offered. Couples who arrive from countries without a screening programme are frequently unaware of their carrier status, and it is worth establishing rather than assuming.

The same regional logic applies to two conditions covered elsewhere on this site: familial Mediterranean fever, which is common here and has implications for pregnancy management, and is dealt with by rheumatology; and the elevated placenta accreta caseload set out under placenta accreta spectrum, which follows from the region’s caesarean rate rather than from anything genetic.

Planning the birth

Almost every diagnosis in fetal medicine converges on the same three decisions: when, how, and where.

When. Timing balances the risk of remaining pregnant against the risk of prematurity, and it moves earlier as the first risk rises. In placenta accreta spectrum, in severe early growth restriction, in significant cholestasis and in some twin complications, delivery is scheduled in advance rather than awaited. Where the date falls before term, antenatal corticosteroids are given to accelerate fetal lung maturity, and magnesium sulphate is given before 32 weeks for fetal neuroprotection. Both are among the most effective interventions in obstetrics and both need to be given in a window, which is another argument for planning rather than reacting.

How. Mode of delivery follows the diagnosis. Placenta previa, accreta spectrum and vasa previa mean planned caesarean. Some fetal conditions favour caesarean; many do not, and a fetal anomaly is not in itself a reason to operate. In twins the mode depends on chorionicity, on the presentation of the leading twin and on the growth pattern, and vaginal birth is often entirely appropriate. Where a previous caesarean is the issue, the decision balances the specific history against this pregnancy — the discussion belongs with obstetrics, which manages delivery.

Where. This is the decision that most often changes the outcome and gets the least attention. A baby with a duct-dependent heart lesion, a diaphragmatic hernia, gastroschisis, an airway mass or severe growth restriction at low gestation should be born in a hospital where the team that will treat it is already present. Transferring a mother before birth is safer than transferring a baby after it, in every one of these conditions. For families travelling from abroad, this is the practical core of the plan: what needs to be on site on the day, and therefore where the last weeks of the pregnancy are spent.

A birth plan in fetal medicine is a written document naming the gestation, the mode, the hospital, the people who need to be present, and what happens immediately after delivery — whether the baby goes to the mother, to a resuscitaire with the neonatal team, or directly to theatre. It is agreed weeks ahead and it is revisited, because the conditions it plans for change.

What fetal medicine cannot do

This specialty is unusually prone to being oversold, so the boundaries deserve stating.

• It cannot detect everything. A normal anomaly scan, a normal NIPT and a normal microarray together still leave conditions that no prenatal test looks for. Many genetic conditions, most metabolic disease, autism, cerebral palsy and the majority of developmental outcomes are not detectable before birth. A complete set of normal results means the tested conditions were not found — nothing wider.
• It cannot make most diagnoses treatable. Fetal therapy exists for a small, defined list: laser for twin-to-twin transfusion, transfusion for fetal anaemia, drainage of some fluid collections, arrhythmia treatment through the mother, and a narrow set of fetal surgical procedures. For everything else the intervention is knowledge — a diagnosis, a plan and the right place to be born.
• It cannot reverse growth restriction. There is no treatment that makes an underperforming placenta perform. Surveillance and timing are the whole of the management, and claims to the contrary are not supported.
• It cannot resolve every uncertainty. Findings of unclear significance are a normal output of high-resolution testing, not a failure of it, and some are still unresolved when the baby is born. The honest version of consent explains that in advance.
• It cannot make the decisions. Where a diagnosis carries a poor prognosis, the choices that follow are the parents’, made with accurate information, adequate time and support — including access to a second opinion, and including palliative and comfort-focused care as a legitimate path rather than an absence of one.

Where the outlook is poor, we say so. A unit that describes every finding as manageable is not being kind.

Your multidisciplinary team

The perinatologist makes the fetal diagnosis, performs the procedures and owns the surveillance schedule and the delivery plan. The obstetrician continues the pregnancy care around that. The fetal cardiologist assesses the heart and, where a defect is found, is the same service that will look after the baby afterwards. The neonatologist joins before birth in every case with a diagnosis, because parents should meet the person who will receive the baby before the day it happens. The clinical geneticist and genetic counsellor handle testing choices, results of uncertain significance and what any of it means for the next pregnancy. The sonographer performs much of the imaging the entire plan rests on. The specialist midwife is the continuity between all of them.

Around them: pediatrics and neonatal intensive care, medical genetics for diagnosis and recurrence risk, cardiology and cardiovascular surgery for maternal and fetal cardiac disease, endocrinology for diabetes and thyroid disease, rheumatology for connective tissue disease in pregnancy, nephrology for kidney disease, hematology for clotting disorders and alloimmunisation, anesthesiology for delivery planning in complex cases, radiology for fetal MRI and for the interventional support that accreta surgery depends on, and pediatric surgery for the anomalies that need an operation in the first days of life.

The international patient journey

Fetal medicine travels differently from surgery, and it travels less well, because the thing being managed has a schedule of its own. Three patterns account for most international referrals.

The first is a remote opinion on imaging already performed. A scan report, the images, and the screening results are reviewed and a written opinion given — whether the finding is what it has been called, whether it is isolated, what would clarify it, and what it means for the rest of the pregnancy. This is the most common request and the one that requires no travel at all.

The second is a single specialist assessment: coming for a detailed scan, a fetal echocardiogram, or an invasive test that is not available or not performed with sufficient volume locally, then returning home to continue care with a written plan. This works well in a defined window and is worth arranging early, because the useful windows in pregnancy are narrow and non-negotiable — chorionicity in the first trimester, the anomaly scan between 18 and 22 weeks, CVS from 11 weeks and amniocentesis from 15.

The third is transfer of care for delivery, which applies to the conditions where where matters: accreta spectrum, a duct-dependent cardiac lesion, a diaphragmatic hernia, an anomaly needing surgery in the first days. This means arriving weeks before the planned date, not days, and it means the maternity and neonatal capacity being confirmed in advance rather than assumed.

Two practical points that are specific to pregnancy. Airlines restrict travel in the third trimester, with the cut-off earlier in multiple pregnancies, and a plan that ignores that will fail. And the imaging matters more than the reports: bring the images themselves, in DICOM format on a disc or drive, not printed screenshots — a scan cannot be reinterpreted from a photograph of a photograph.