Fetal growth restriction

Red Flags

Reversed end-diastolic flow in umbilical artery — admit; antenatal corticosteroids if 24–34 weeks; deliver per gestation and ductus venosus a-wave; involve maternal-fetal medicine^[1]
Absent end-diastolic flow with abnormal CTG or biophysical profile — deliver at any gestation ≥26 weeks if fetal viability anticipated^[1]
Severe FGR (estimated fetal weight <3rd centile) with reduced fetal movements at any gestation — same-day obstetric review including CTG and Doppler^[1]
Suspected FGR with maternal pre-eclampsia, placental abruption, or PPROM — admit; deliver per maternal and fetal status^[1]

First-line treatment

Interventions

Distinguish small-for-gestational-age from FGR^[1]
FGR = pathological failure to reach growth potential; SGA = constitutionally small with normal Dopplers and growth velocity. Delphi-consensus criteria combine size centiles with Doppler indices
Identify modifiable maternal causes^[1]
Smoking cessation; treat anaemia, thyroid disease, hypertension, infection; substance use counselling; address malnutrition
Stratified surveillance pathway^[1]
Late-onset (≥32 weeks): UA + MCA Doppler, growth every 2 weeks, CTG. Early-onset (<32 weeks): add ductus venosus, biophysical profile; tertiary maternal-fetal medicine input
Timing of delivery^[1]
EFW ≥3rd centile + normal Doppler: deliver at 37 weeks. EFW <3rd centile or abnormal UA: 36–37 weeks. AEDF: 34 weeks. REDF: 30–32 weeks. Abnormal DV or non-reassuring CTG: deliver after corticosteroid course completion if gestation permits

First-line drug therapy

Drug	Class	Adult	Paediatric	Notes
Antenatal corticosteroids — betamethasone or dexamethasone^[1]	Glucocorticoid for fetal lung maturation	Betamethasone 12 mg IM × 2 doses 24 h apart; dexamethasone 6 mg IM × 4 doses 12 h apart	—	All anticipated preterm delivery 24+0 to 34+6 weeks; consider single rescue course if delivery still anticipated >7 days after first course
Magnesium sulfate (fetal neuroprotection)^[1]	Tocolytic / neuroprotective	4 g IV over 20 min, then 1 g/h IV until delivery or 24 h	—	Anticipated delivery <32 weeks; reduces cerebral palsy risk by ~30% in survivors; monitor reflexes, respiration, urine output
Aspirin (FGR prevention in subsequent pregnancy)^[1]	Antiplatelet (low-dose)	150 mg PO at night from 12 weeks until 36 weeks (or term)	—	Prior pregnancy with FGR or pre-eclampsia, or other high-risk features; reduces recurrence; may be combined with calcium 1 g/day where dietary intake low

Antenatal corticosteroids — betamethasone or dexamethasone^[1]

Glucocorticoid for fetal lung maturation

Adult: Betamethasone 12 mg IM × 2 doses 24 h apart; dexamethasone 6 mg IM × 4 doses 12 h apart
Paediatric: —

All anticipated preterm delivery 24+0 to 34+6 weeks; consider single rescue course if delivery still anticipated >7 days after first course

Magnesium sulfate (fetal neuroprotection)^[1]

Tocolytic / neuroprotective

Adult: 4 g IV over 20 min, then 1 g/h IV until delivery or 24 h
Paediatric: —

Anticipated delivery <32 weeks; reduces cerebral palsy risk by ~30% in survivors; monitor reflexes, respiration, urine output

Aspirin (FGR prevention in subsequent pregnancy)^[1]

Antiplatelet (low-dose)

Adult: 150 mg PO at night from 12 weeks until 36 weeks (or term)
Paediatric: —

Prior pregnancy with FGR or pre-eclampsia, or other high-risk features; reduces recurrence; may be combined with calcium 1 g/day where dietary intake low

Safety-net

Reduced or absent fetal movements at any gestation — same-day maternity assessment unit; do not wait until next antenatal visit^[1]
Attend every growth scan and Doppler appointment — most FGR deterioration is silent^[1]
Stop smoking and limit caffeine; addressing modifiable factors meaningfully changes neonatal outcomes^[1]

Referral criteria

Early-onset FGR (<32 weeks)Tertiary maternal-fetal medicine and neonatal team^[1]
Abnormal umbilical artery Doppler (PI >95th, absent or reversed end-diastolic flow)Maternal-fetal medicine for delivery planning and serial DV/CTG surveillance^[1]
Suspected co-existent pre-eclampsia or placental abruptionObstetric admission^[1]
Recurrent FGR or unexplained stillbirthPre-conception MFM and consideration of thrombophilia, autoimmune workup^[1]

Clinical summary

Identification, surveillance, and timing of delivery for early- and late-onset fetal growth restriction in singleton pregnancies.

References

1.FOGSI Focus on Fetal Growth Restriction (2018, refreshed); FIGO consensus on FGR (2021); ISUOG Practice Guidelines on Doppler in Obstetrics (2021)