Antepartum fetal assessment (fetal surveillance) uses tests of fetal heart rate, movement, amniotic fluid, and blood flow to detect a fetus at risk of hypoxemia or stillbirth before labor, so that delivery or further evaluation can be timed safely.

Why these tests work: a well-oxygenated fetus with an intact central nervous system shows heart rate accelerations, normal variability, breathing movements, body movements, and muscle tone. As hypoxemia develops, these activities are lost in a rough reverse order of their development — accelerations and breathing movements disappear first, tone last. Chronic placental insufficiency redistributes blood away from the fetal kidneys, so urine output falls and oligohydramnios develops.

Common indications for surveillance

• Maternal: chronic or gestational hypertension, preeclampsia, pregestational or poorly controlled gestational diabetes, lupus, chronic kidney disease, advanced maternal age, obesity
• Fetal/pregnancy: fetal growth restriction (FGR), decreased fetal movement, oligohydramnios or polyhydramnios, multiple gestation, post-term pregnancy (41 weeks or more), previous stillbirth, Rh alloimmunization

Surveillance usually starts at about 32 weeks (earlier for very high-risk conditions) and is repeated weekly or twice weekly depending on the indication.

Fetal movement counting ("kick counts")

• Client lies on her side and counts distinct movements; a common method is 10 movements within 2 hours. No single counting method is proven best; any perceived decrease from the client's usual pattern matters most
• Decreased fetal movement is a warning sign and warrants same-day evaluation (NST or BPP), not waiting until the next appointment

Fetal heart rate (FHR) baseline and patterns (same definitions as in labor)

Causes of fetal tachycardia: maternal fever or infection, dehydration, maternal hyperthyroidism, beta-agonists (terbutaline), stimulant drugs, fetal anemia, fetal hypoxemia, fetal tachyarrhythmia.

Causes of decreased variability: fetal sleep cycle (usually 20–40 minutes), maternal opioids, sedatives or magnesium sulfate, prematurity, fetal hypoxemia/acidemia, fetal neurologic or cardiac anomalies, fetal infection.

Nonstress test (NST)

• Client semi-Fowler's or lateral tilt; external transducer and toco for 20 minutes (extended to 40 minutes to allow for a sleep cycle)
• Reactive (reassuring): at least 2 accelerations in 20 minutes meeting the gestational-age criteria above
• Nonreactive: criteria not met in 40 minutes → needs further testing (vibroacoustic stimulation, BPP, or CST)
• Decelerations during an NST: brief nonrepetitive variable decelerations (< 30 seconds) are usually benign; 3 or more variable decelerations in 20 minutes, or any deceleration lasting 1 minute or longer, need further evaluation (BPP, ultrasound)
• Vibroacoustic stimulation (a sound device on the maternal abdomen) can wake the fetus and shorten testing time

Biophysical profile (BPP) — 5 components, each scored 2 (present) or 0 (absent) within 30 minutes

• 8–10: normal (8/10 with oligohydramnios still needs further evaluation)
• 6: equivocal — repeat or deliver depending on gestational age
• 4 or less: abnormal — delivery is usually considered
• Modified BPP = NST + amniotic fluid assessment; common for routine surveillance

Amniotic fluid measurement

• Oligohydramnios: single deepest pocket < 2 cm or amniotic fluid index (AFI) ≤ 5 cm. The deepest-pocket method is preferred because it leads to fewer unnecessary interventions
• Polyhydramnios: deepest pocket ≥ 8 cm or AFI ≥ 24–25 cm

Contraction stress test (CST)

• Evaluates fetal response to reduced placental flow during contractions. Needs 3 contractions of at least 40 seconds in 10 minutes, induced by nipple stimulation or low-dose oxytocin
• Negative (reassuring): no late or significant variable decelerations
• Positive (abnormal): late decelerations with 50% or more of contractions → suggests uteroplacental insufficiency
• Equivocal or unsatisfactory results need repeat testing
• Contraindications (same as for labor): placenta previa, vasa previa, prior classical cesarean or extensive uterine surgery, preterm premature rupture of membranes, high risk of preterm labor
• Now used less often than the BPP

Doppler velocimetry

• Umbilical artery Doppler is used for FGR: absent or reversed end-diastolic flow signals severe placental resistance and changes timing of delivery
• Middle cerebral artery (MCA) Doppler peak systolic velocity detects fetal anemia (e.g., Rh or other alloimmunization)

Other assessments

• Ultrasound: dating, anatomy, growth, placental location, fluid
• Amniocentesis: genetic diagnosis (usually from 15 weeks), infection, or alloimmunization evaluation
• Chorionic villus sampling (10–13 weeks), cell-free DNA screening, maternal serum screening (alpha-fetoprotein, quad screen) — screening vs. diagnostic tests are covered in prenatal care

• Choice and frequency of testing depend on the indication (e.g., weekly for many chronic conditions, twice weekly for some high-risk states)
• Reassuring results usually predict low risk of stillbirth for about 1 week if the maternal condition is stable; testing is repeated sooner if the condition changes or fetal movement decreases
• Abnormal results lead to further testing, admission for continuous monitoring, antenatal corticosteroids if preterm delivery is likely, magnesium sulfate for neuroprotection when delivery is expected before 32 weeks, and delivery planning
• A positive CST or BPP of 4 or less near term generally leads to delivery; the route depends on fetal tolerance of labor and obstetric factors

Listed in priority order.

1. Respond to an abnormal or concerning tracing
   • If the NST shows minimal variability and no accelerations, first reposition the client to the left or right lateral position to relieve aortocaval compression, check maternal vital signs, and consider hydration
   • Extend the test to allow for a fetal sleep cycle; use vibroacoustic stimulation if ordered
   • Report nonreactive tests, decelerations, bradycardia, or tachycardia promptly
2. Maternal safety during testing
   • Avoid the supine position (supine hypotension)
   • During a CST with oxytocin, use an infusion pump and stop the infusion for excessive contractions or abnormal FHR
3. Accurate monitoring
   • Apply the ultrasound transducer over the fetal back (Leopold maneuvers), the toco over the fundus; distinguish maternal from fetal heart rate (check maternal pulse)
   • Mark fetal movements on the tracing
4. Procedures
   • Amniocentesis: obtain consent, baseline vital signs and FHR; have the client void before the procedure after about 20 weeks; monitor FHR and for cramping, fluid leakage, bleeding, or fever afterward
   • Give Rh(D) immune globulin to an unsensitized Rh-negative client after amniocentesis, CVS, or bleeding (300 mcg IM within 72 hours)
5. Communication — explain the purpose and results within scope; the interpretation leading to delivery decisions is made by the obstetric provider, but the nurse identifies, intervenes, and reports

• Start daily fetal movement awareness in the third trimester; lie on the side after a meal and count movements
• Report decreased or absent movement the same day — do not wait until the next day or visit
• Before an NST: eat normally; smoking and some drugs reduce fetal activity
• A reactive NST is reassuring for about a week, but new symptoms (bleeding, fluid leakage, pain, headache, visual changes, decreased movement) need immediate evaluation
• Explain that a nonreactive result is common during fetal sleep and does not by itself mean the fetus is compromised

• Normal FHR baseline 110–160 bpm; moderate variability 6–25 bpm
• Acceleration ≥ 32 weeks = 15 bpm × 15 seconds; < 32 weeks = 10 × 10
• Reactive NST: 2 or more accelerations in 20 minutes
• Nonreactive NST → reposition, extend for sleep cycle, stimulate, then BPP or CST
• BPP: 5 components × 2 points; 8–10 normal, 4 or less abnormal
• Oligohydramnios: deepest pocket < 2 cm or AFI ≤ 5 cm
• Positive CST = late decelerations with ≥ 50% of contractions (abnormal)
• CST contraindications = labor contraindications (previa, prior classical cesarean)
• Decreased fetal movement → same-day evaluation
• Rh-negative client: Rh immune globulin after invasive procedures