Early-Onset Fetal Growth Restriction

Early onset fetal growth restriction is growth restriction diagnosed before 32 weeks. It reflects severe placental disease and is often accompanied by preeclampsia. It matters because it carries high perinatal mortality and prematurity related disability, and delivery timing balances fetal acidosis against immaturity.

It is defined by any one of:

• An abdominal circumference or estimated weight below the 3rd centile.
• Absent end diastolic flow in the umbilical artery.
• Both a size below the 10th centile and raised uterine and umbilical artery resistance.

• Preeclampsia is common.
• Risk factors: previous growth restriction, chronic hypertension, antiphospholipid syndrome, kidney disease, thrombophilia, lupus.
• Management is best in a unit with a neonatal intensive care unit.

Fundal height lags by more than 3 cm before 32 weeks, often with reduced fetal movements and hypertension. Women may have no symptoms.

• Small abdomen with oligohydramnios.
• Raised blood pressure and proteinuria.
• Differential diagnosis: wrong dates, constitutionally small fetus, chromosomal abnormality, congenital infection, preeclampsia without growth restriction, fetal anomaly.
• Complications: stillbirth, fetal acidosis, extreme preterm birth, necrotising enterocolitis, cerebral palsy, bronchopulmonary dysplasia, maternal preeclampsia and abruption.

The approach is serial scanning with staging by Doppler.

• Ultrasound:
  • Abdominal circumference or estimated fetal weight below the 3rd centile.
  • Absent or reversed end diastolic flow.
  • Size below the 10th centile with umbilical artery pulsatility index above the 95th centile and uterine artery pulsatility index above the 95th centile.
• Ductus venosus Doppler (absent or reversed a wave is a sign of imminent acidosis), middle cerebral artery Doppler, liquor volume.
• Computerised cardiotocography short term variation where available, with abnormal values guiding delivery; otherwise cardiotocography for baseline, variability and decelerations.
• Maternal tests: blood pressure, urine protein, full blood count, creatinine, liver enzymes, antiphospholipid antibodies, syphilis, HIV, malaria; amniocentesis if anomaly is found.

The principle is intensive surveillance and delivery when the fetus shows signs of acidosis or at the gestation set by the Doppler stage.

• Supportive: admit from 26 weeks when end diastolic flow is absent or reversed; left lateral rest; cardiotocography once or twice daily; Dopplers twice weekly; neonatal unit informed; counselling about prognosis before 26 weeks.
• Pharmacological:
  • Betamethasone 12 mg IM twice, 24 hours apart, from 24 weeks to 34 weeks and 6 days before planned delivery.
  • Magnesium sulphate 4 g IV over 20 minutes then 1 g per hour until delivery for 24 hours at most before 32 weeks.
  • Stop magnesium for absent patellar reflexes, respiratory rate below 12 per minute or urine below 30 mL per hour, with calcium gluconate 1 g IV over 10 minutes for toxicity.
  • Labetalol 200 mg oral every 8 to 12 hours (maximum 2.4 g daily) or nifedipine modified release 30 to 60 mg oral once daily (maximum 120 mg) for hypertension.
  • Enoxaparin 40 mg subcutaneous daily with aspirin 150 mg oral at night for antiphospholipid syndrome.
  • Aspirin 150 mg oral at night from 12 weeks to 36 weeks in the next pregnancy.
• Procedures:
  • Delivery by caesarean section at 30 to 32 weeks for reversed end diastolic flow, 34 weeks for absent end diastolic flow, and at once for abnormal ductus venosus flow, pathological cardiotocography or severe preeclampsia after steroid cover where time allows.
  • Induction at 37 weeks if umbilical artery Doppler stays normal.
• Special groups:
  • Severe preeclampsia needs magnesium sulphate 4 g IV then 1 g per hour for 24 hours after birth and labetalol 20 mg IV then 40 mg, 80 mg and 80 mg at 10 minute intervals (maximum 220 mg) for blood pressure 160/110 mmHg or more.
  • Preterm newborns need kangaroo mother care and glucose checks, with glucose below 2.6 mmol/L treated by dextrose 10 percent 2 mL/kg IV over 10 minutes then 80 mL/kg per day.
• Red flags: absent or reversed end diastolic flow, abnormal ductus venosus, pathological cardiotocography, reduced fetal movements, severe hypertension, bleeding.
• Follow-up: Dopplers twice weekly; daily cardiotocography; growth every 2 weeks; neonatal and developmental review after birth.