Antepartum fetal surveillance

• Antepartum fetal surveillance is the ongoing check that a baby is well before labour, using the mother's report of fetal movements and simple tests of the fetal heart and environment, so that a compromised baby can be delivered before harm occurs.
• It is needed only in pregnancies where something increases the risk of stillbirth: maternal disease, placental or fetal growth problems, reduced fetal movements, post-term or twin pregnancy, a previous stillbirth, and similar situations (^{[1] [2]}).
• The usual first check is either a non-stress test (NST, an external recording of the fetal heart without contractions) or, when more than one question must be answered, a biophysical profile (BPP). ^[1]
• The tests use cut-offs, not vague impressions: 2 accelerations of at least 15 beats per minute lasting at least 15 seconds for a reactive NST after 32 weeks, and a BPP score of at least 8 out of 10 to call normal (^[1]).
• Kick counting has a place but is not a substitute for formal testing; NICE advises women to contact services about reduced movements from 24 weeks, while WHO does not recommend routine formal counting as a population screening tool (^{[5] [6] [7]}). ^[4]
• Always ask what a positive result changes: the purpose is to reduce stillbirth, so every abnormal result must lead to a plan, usually repeat or extended testing and, when severe, timely delivery.

By the end of this page you should be able to:

1. Name the risk conditions that make antepartum fetal surveillance sensible, and the gestation at which testing usually starts.
2. Explain the physical principle behind a non-stress test, a contraction stress test, a biophysical profile and an umbilical artery Doppler.
3. Apply the cut-offs that separate reactive from non-reactive, normal from equivocal and abnormal BPP, and normal from abnormal Doppler findings.
4. Describe a stepwise management pathway from reassurance to repeat testing to delivery, including when to escalate.
5. Document and communicate a surveillance result so that the next reader can act on it.
6. Avoid the common pitfalls: conflating a non-reactive tracing with fetal compromise, counting movements poorly, testing in a low-risk pregnancy and ignoring an out-of-date result.

A surveillance plan has only one purpose: to discover fetal compromise early enough that action, usually earlier delivery, changes the outcome. If the result will not change management, the test should not be done (^[1]).

Every patient should move through the same four steps, even though the tests used at each step differ by risk condition.

1. Risk stratification. Decide whether this pregnancy merits surveillance at all, what the risk is, and from what gestation testing should start. This is the single most important step and is best done at booking and again when a complication develops.
2. Baseline assessment. Establish gestational age, placental site and liquor, fetal growth and, where indicated, a baseline fetal heart rate pattern. Without a reliable gestational age no surveillance plan is interpretable.
3. Scheduled surveillance. Apply the chosen test on the agreed interval, record the result in a standard way, and act on it.
4. Reassessment and escalation. A normal result is valid only for the interval agreed (commonly one week, or less in high risk). Any new symptom, reduced movement, or abnormal result moves the patient up the intensity ladder.

The frequency follows the condition, not a routine. In the NICHD indications table, testing is weekly to twice weekly in most high-risk states and daily in severe hypertension or preterm prelabour rupture of membranes; in other words, the sicker the placental or maternal state, the denser the testing (^[1]). A normal BPP has a false-negative (stillbirth within one week) rate of 0.07 to 0.08% (^[1]).

Surveillance belongs to the pregnancies on the right of this list, not to the uncomplicated pregnancy. Evidence for testing in low-risk women is absent, and testing the low-risk group produces false positives rather than benefit (^{[1] [2]}).

Indications by category (^{[1] [2] [4]}):

• Placental and fetal growth problems: fetal growth restriction or small for gestational age, oligohydramnios, a growth-discordant twin, and abnormal serum markers of placental function.
• Maternal medical disease: pre-gestational or gestational diabetes (diabetes needing insulin), chronic hypertension, renal disease, systemic lupus erythematosus, cholestasis of pregnancy, and thyroid disease.
• Hypertensive disorders of pregnancy: pregnancy-induced hypertension, pre-eclampsia, in particular severe or early-onset disease.
• Obstetric complications: post-term pregnancy (at or after 40 weeks), preterm prelabour rupture of membranes, multiple pregnancy (twins, especially monochorionic, and triplets), previous stillbirth, and advanced maternal age or high parity where other risk is present.
• Fetal and movement concerns: decreased fetal movement, for which guidelines recommend at minimum an NST and amniotic fluid assessment (^[1]).
• Regional and service context: ACOG PB 229 reaffirms the view that antepartum testing may be appropriate for any pregnancy in which the risk of antepartum fetal demise is increased, and lists conditions in its indications table (^[2]). NICE recommends formal risk assessment for growth restriction at booking and in the second trimester and RCOG Green-top 31 sets out the FGR pathway, including Doppler surveillance (^{[4] [5]}).

Gestational age is condition-specific. Examples from the indications table are: growth restriction, at diagnosis; chronic hypertension, from 26 weeks; insulin-requiring diabetes without hypertension, renal disease or growth restriction, from 32 weeks; previous stillbirth, most authors at 32 to 34 weeks or one week before the previous loss; post-term, after 40 weeks; oligohydramnios, at diagnosis (^[1]). ACOG similarly supports initiating assessment after 40 weeks in post-dates pregnancy (^[1]). Testing before 32 weeks rarely has a clear evidence base and should be a senior decision (^[1]).

NICE also asks for a risk assessment for growth restriction at booking and again in the second trimester, with referral to the RCOG guideline as one example of professional guidance (^[5]). WHO's 2016 ANC guideline covers maternal and fetal assessment among its routine recommendations; ACOG PB 229 (2021, reaffirmed 2024) is the principal US guidance and updates ACOG Practice Bulletin 145 (2014) with a limited change to align with Committee Opinion 828 on indications for outpatient surveillance and updated information on fetal kick counts (^{[6] [2]}). ^[4]

Each test answers a different physiological question; choose the test that fits the question rather than running all of them.

• Fetal movement counting. The mother's own report is the only truly continuous monitor. Two counting methods are described: a fixed time count over a defined interval (traditionally 12 hours) and a fixed number method, recording the time to 10 movements, which is generally associated with higher compliance (^[8]). Cardiff's "count of ten", used in the maternity sources, expects ten movements within 12 hours counting from 09:00; an alternative daily method uses three one-hour counts, multiplies by four and regards under 10 in that equivalent as compromise (^[7]). ^[6]
• Non-stress test (NST). An external ultrasound probe records fetal heart rate while a second transducer records uterine activity; no contractions are induced. It rests on the principle that a normally oxygenated brain produces reactive fetal heart rate accelerations with movement, so NST is mainly a screen for fetal well-being rather than distress, with a false-negative rate of about 0.3% and a false-positive rate of about 55% (^[1]).
• Biophysical profile (BPP). Five components are scored in 30 minutes: reactive NST, fetal breathing of at least 30 seconds, at least three gross body movements, at least one episode of normal tone, and an amniotic fluid pocket above 2 cm (or AFI above 5 cm). Each present component scores 2; the maximum is 10 (^{[1] [7]}). ^[6]
• Modified biophysical profile (mBPP). Only the NST plus amniotic fluid index, used as a screening version: normal if the NST is reactive and the AFI is above 5 cm, abnormal if either is not (^[1]).
• Contraction stress test (CST). Cardiotocography during at least three contractions of at least 40 seconds in ten minutes, to see whether the fetal heart shows late decelerations when oxygen supply is briefly challenged. It is contraindicated where contractions are unwise, for example placenta praevia (^[1]).
• Doppler ultrasound. Umbilical artery waveform shows placental resistance: normal high diastolic flow, falling to diminished, absent, then reversed end-diastolic flow as placental villous disease worsens (^{[1] [3]}). Middle cerebral artery Doppler picks up the "brain-sparing" vasodilation of hypoxia, uterine artery Doppler reflects maternal placental perfusion, and ductus venosus and other venous waveforms reflect fetal cardiac function (^[1]).
• Ultrasound for growth and fluid. Symphysis-fundal height screening after 24 weeks, with growth scanning when large or small for dates; NICE does not recommend routine third-trimester scans in uncomplicated singleton pregnancies (^[5]). ^[4]

ACOG supports umbilical artery Doppler only in the management of suspected intrauterine growth restriction, with delivery decisions based on Doppler plus other tests of well-being (^{[1] [3]}). RCOG Green-top 31 sets out the SGA and FGR pathway including Doppler monitoring (^[4]).

Checks on speed and safety: vibroacoustic stimulation shortens a falsely non-reactive trace in fetal sleep (it shifts non-REM to REM sleep), and fetal manipulation is a recognised alternative; neither should be used to turn a genuinely abnormal trace reassuring (^{[7] [1]}).

These are the cut-offs that change the plan. Write the actual numbers, not "normal" alone.

Text interpretation of the BPP: a 6 of 10 score often just needs repeat testing within 24 hours because breathing or movement can be temporarily absent in a sleep cycle, whereas 4 or below carries a true positive rate of about 50% and usually triggers delivery if the fetus is viable (^[1]). The CST has the lowest false-negative rate (0.04%) but the lowest specificity, with 35 to 65% false positives, so a positive CST is not treated on its own; a backup test and clinical context matter (^[1]).

The step ladder, from least to most aggressive:

1. Reassure and re-establish normal. A mother worried about movements is assessed with an NST and fluid, plus a growth measurement if dates suggest it. If the NST is reactive, fluid is normal and growth is on track, reassure, document and review at the usual interval (^{[4] [5]}).
2. Repeat or extend testing within 24 hours. For a single non-reactive NST, an equivocal BPP (6 of 10) or an unsatisfactory CST, repeat rather than act, because fetal sleep and transient factors commonly explain the result. Vibroacoustic stimulation and extension to 40 minutes are accepted first moves (^{[1] [7]}).
3. Increase intensity. Move from weekly to twice weekly, or to a full BPP plus Doppler, add umbilical artery Doppler in growth restriction and uterine plus middle cerebral Doppler where placental disease is suspected. In severe hypertension or PPROM testing becomes daily (^{[1] [3]}).
4. Treat the cause. Correct what can be corrected: maternal hypertension control, diabetes glycaemic control, hydration, bed rest with monitoring where indicated, antenatal corticosteroids if preterm delivery is likely, and always delivery of the placenta as the definitive treatment of placental disease. No antenatal test treats the fetus; it only informs the timing of these decisions (^[2]).
5. Deliver. The endpoint of surveillance is delivery when the risk of continuing exceeds the risk of prematurity, when tests are repeatedly abnormal, or when a condition such as severe pre-eclampsia, reversed end-diastolic flow, or a non-reassuring trace in a post-term pregnancy makes waiting unsafe. The final decision balances gestation, test severity, maternal condition and local capability (^{[1] [3]}).

RCOG Green-top 57 also links reduced movement to assessment, and RCOG Green-top 31 links confirmed fetal growth restriction to umbilical artery Doppler surveillance and delivery timing decisions (^[4]). NICE recommends asking about movements at every visit from 24 weeks and never leaving a woman who reports reduced fetal movement without an assessment (^[5]).

Escalate the same day when any of the following apply:

• A confirmed positive or repeatedly abnormal CST, a BPP of 4 or below, or absent/reversed end-diastolic flow in the umbilical artery.
• Non-reactive NST combined with oligohydramnios, growth restriction or maternal disease, which turns a possibly false positive into probable compromise.
• Decreased fetal movement at any gestation above 24 weeks, particularly with any abnormal test or suspected growth restriction; NICE and RCOG both expect prompt assessment and, where appropriate, consultant review (^{[5] [4]}).
• Severe hypertension or post-term pregnancy over 41 weeks with any non-reassuring feature.
• A maternal condition that needs a specialist (for example, fetal medicine for twins, diabetes, cholestasis requiring early delivery, or maternal cardiac or renal disease).

Referral domains should be named rather than implied: fetal medicine for Doppler interpretation and growth restriction; neonatology if preterm delivery is planned; anaesthetics and critical care if maternal disease is severe; and social or safeguarding referral where late booking, domestic abuse or complex social factors (NICE NG201 section 1.2.3) are part of the risk picture (^[5]). A plain handover includes the risk condition, the gestation, the last test and its date, the next planned test and the contact person; if it is not written it will be lost. ^[4]

Good documentation is part of the test, not paperwork after it. Every entry should state:

• Why surveillance is being done (the risk condition and gestation), because the same tracing means different things at 28 and 38 weeks.
• Which test, when it was done, who interpreted it, and the actual values: baseline rate and variability, presence and number of accelerations, contraction count, BPP score component by component, AFI or largest pocket, and Doppler velocities and ratios used.
• The interpretation (reactive or non-reactive; normal, equivocal, abnormal; and the Doppler category) written out in words, not only ticked boxes.
• What was communicated to the woman, in which language, and what she was asked to report (especially reduced movements, bleeding or pain).
• The plan with a date, time and owner, plus escalation triggers: for example, "repeat BPP tomorrow 09:00; come in immediately if movements reduce."
• Continuity items: medication, allergies, prior caesareans, and the phone number for the maternity assessment unit.

NICE requires that at every antenatal contact the records are updated with history, test results, examination findings, medicines and discussions, and that reliable interpreting is provided with independent interpreters rather than family members (^[5]). WHO's 2016 guideline and ACOG both frame antenatal care around women's right to information and informed consent, so the plan must be shared with the woman and her partner rather than decided for them (^{[6] [2]}).

• Treating a non-reactive NST as fetal distress. A non-reactive trace is only that; with a roughly 55% false-positive rate it usually normalises with repeat testing, vibroacoustic stimulation or a full BPP, and it must be paired with context before delivery is considered (^[1]).
• Confusing a CST "equivocal" with "positive". Intermittent late decelerations or significant variables call for repeat or back-up testing, not immediate delivery; unsatisfactory means you did not get enough contractions (^[1]).
• Over-testing the low-risk pregnancy. Evidence for surveillance in low-risk women is absent, and routine third-trimester scanning in uncomplicated singletons is not recommended by NICE. Every false positive carries an iatrogenic cost (^{[5] [1]}).
• Using kick counts as a test. There is no universally accepted alarm limit and the methods vary; formal counting can reassure without improving outcomes in some trials. Kick counting is education and a trigger for formal assessment, not a screening test in its own right (^{[8] [1] [7]}). NICE advised against routine counting in 2004, while RCOG, NICE and ACOG all require women to be told to report a reduction (^{[5] [7]}).
• Ignoring gestational age when starting testing. Testing at 28 weeks for a reason appropriate only above 32 weeks wastes resources and produces non-reactive traces because of fetal immaturity; likewise post-term assessment starts at 40 weeks (^{[1] [2]}).
• Letting a BPP component be missed. Tone and breathing are the most often skipped in practice; score each of the five elements and never silently substitute a normal-looking trace for the formal components (^{[1] [7]}).
• Not acting on reversed flow. Absent or reversed end-diastolic flow in a growth-restricted fetus is severe disease; it must be escalated rather than repeated routinely (^{[1] [3]}).
• Documentation that cannot be read later. A ticked box without numbers, date and owner turns a surveillance system into a liability; in a multiple pregnancy record every fetus separately.
• Missing the social and ethnic risk pattern. NICE NG201 quotes MBRRACE-UK data showing higher maternal and stillbirth risk in some ethnic groups and in deprivation; a woman in a high-risk social situation needs closer surveillance and additional support, not routine care (^[5]).

• Fetal growth restriction: RCOG Green-top 31 (3rd edition, 2024) provides the Doppler-based pathway: umbilical artery surveillance, middle cerebral and ductus venosus assessment in worsening disease, customised growth charts, and timing of delivery; note the July 2026 English NHS correction on Intergrowth charts (^[4]). ^[3]
• Twins and triplets: RCOG and others recommend more frequent surveillance in discordant or monochorionic twins from diagnosis and a lower threshold for delivery, but good evidence on timing is sparse (^[1]).
• Diabetes: insulin-requiring diabetes usually starts surveillance around 32 weeks, diet-controlled gestational diabetes has no evidence base for routine testing, and the modalities of choice (NST, CST or BPP) remain unsettled by trials (^[1]).
• Previous stillbirth: a two- to ten-fold increased risk; begins at 32 to 34 weeks or one week before the prior loss, with weekly CST or modified BPP as options (^[1]).
• Low resource: in settings without ultrasound or cardiotocography, fetal movement awareness, symphysis-fundal height plotting and bedside heart-rate auscultation are the realistic tools; any of them is better than nothing when combined with a clear rule for when to send the woman to the next level, and systems should invest first in the NST and amniotic fluid assessment that give the most information per cost (^{[1] [6]}). WHO's 2016 guideline frames antenatal care around person-centred, rights-based assessment rather than technology alone (^[6]).

• Antepartum fetal surveillance is a monitoring strategy for pregnancies with increased stillbirth risk; it is not a diagnosis and has no place in routine low-risk care.
• Surveillance should begin at a gestation dictated by the risk condition, commonly 26 to 34 weeks, after 40 weeks in post-dates pregnancy, and whenever a complication develops.
• Risk stratification precedes every test: the same trace means different things depending on why testing is being done.
• A reactive NST after 32 weeks needs at least two accelerations of 15 bpm lasting at least 15 seconds within 20 minutes; extending to 40 minutes or using vibroacoustic stimulation is acceptable (^[1]).
• A BPP of at least 8 of 10 is normal, 6 is equivocal, and 4 or fewer is abnormal; a normal BPP carries about a 1 in 1300 fetal-death rate within a week (^[1]).
• The modified BPP (reactive NST plus AFI above 5 cm) is the usual screening test; CST has the lowest false-negative rate but the most false positives and is contraindicated where contractions are unwise.
• Doppler of the umbilical artery shows placental resistance; absent or reversed end-diastolic flow in growth restriction is severe and requires escalation, not repetition.
• Kick counting uses varied methods and has no single alarm limit; it is education and a trigger for formal testing, not a screening test (^{[8] [7]}).
• NICE advises women from 24 weeks to report reduced movements at any hour and requires an assessment; WHO (2016) does not recommend formal routine counting as a population measure but supports women's awareness (^{[5] [6]}).
• ACOG PB 229 (2021, reaffirmed 2024) and RCOG GTG 31 (2024) and GTG 57 (2026) are the principal regional guidelines and must be named and dated in practice (^{[2] [4]}).
• Every normal result expires with its agreed interval; a new symptom or abnormal result moves the patient up the intensity ladder.
• Document indication, gestation, test, values, interpretation, communication and a dated plan with an owner; an undocumented test is no better than an undone one.

Antepartum haemorrhage; diabetes in pregnancy; fetal growth restriction and small-for-gestational-age fetus; hypertensive disorders of pregnancy; induction of labour; multiple pregnancy; post-term pregnancy; previous stillbirth; reduced fetal movements; preterm prelabour rupture of membranes (all MedGrasp obstetrics topics; pending verified entries linked as plain text when available).