Multifetal pregnancy

Red Flags

Monochorionic monoamniotic twins or any monochorionic pregnancy with growth discordance, polyhydramnios/oligohydramnios sequence, or amniotic fluid disparity — twin-to-twin transfusion syndrome; tertiary fetal medicine same-week^[1]
Threatened preterm labour <34 weeks in twins — admit; corticosteroid; magnesium sulfate for neuroprotection if <32 weeks; tocolysis only to complete steroid course^[1]
Discordant fetal anomaly or selective intrauterine growth restriction in monochorionic pair — fetal medicine; selective fetoscopic laser or selective termination per legal/ethical framework^[1]
Severe pre-eclampsia in multifetal pregnancy — admit; deliver as for singleton; multifetal pregnancy increases pre-eclampsia and HELLP risk^[1]

Chorionicity-driven antenatal pathway^[1]
Dichorionic-diamniotic: scan every 4 weeks from 24, deliver 37–38 weeks. Monochorionic-diamniotic: scan every 2 weeks from 16, deliver 36–37 weeks. Monochorionic-monoamniotic: tertiary surveillance, deliver 32–34 weeks via caesarean
Cervical length screening for preterm birth prevention^[1]
Transvaginal cervical length 18–24 weeks; vaginal progesterone 200 mg PO/PV daily for short cervix <25 mm; cerclage selective in twin pregnancies; pessary not routinely indicated
Nutritional support and supplementation^[1]
Caloric increase ~300 kcal/day above singleton; calcium 2000–2500 mg/day; iron-folic acid double-dose; vitamin D and B12 per status
Mode of delivery^[1]
Vaginal delivery for cephalic-cephalic dichorionic twins with experienced operator; caesarean for non-cephalic first twin, monochorionic-monoamniotic, prior caesarean, or maternal/fetal indication

Drug	Class	Adult	Paediatric	Notes
Antenatal corticosteroids^[1]	Glucocorticoid for fetal lung maturation	Betamethasone 12 mg IM × 2 doses 24 h apart, or dexamethasone 6 mg IM × 4 doses 12 h apart	—	All anticipated preterm twin delivery 24+0 to 34+6 weeks; complete course before delivery if possible; rescue course if delivery delayed >7 days
Magnesium sulfate (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
Vaginal progesterone^[1]	Progestogen	200 mg vaginal pessary or gel daily from 16–22 weeks until 36 weeks for short cervix	—	Preterm birth prevention in singleton with short cervix; in twins limited evidence but considered for short cervix; not for routine multifetal use
Aspirin (pre-eclampsia prevention)^[1]	Antiplatelet (low-dose)	150 mg PO at night from 12+0 to 36+0 weeks	—	All twin pregnancies have elevated pre-eclampsia risk and qualify for prophylaxis

Antenatal corticosteroids^[1]

Glucocorticoid for fetal lung maturation

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

All anticipated preterm twin delivery 24+0 to 34+6 weeks; complete course before delivery if possible; rescue course if delivery delayed >7 days

Magnesium sulfate (neuroprotection)^[1]

Tocolytic / neuroprotective

Anticipated delivery <32 weeks; reduces cerebral palsy risk by ~30% in survivors

Vaginal progesterone^[1]

Progestogen

Adult: 200 mg vaginal pessary or gel daily from 16–22 weeks until 36 weeks for short cervix
Paediatric: —

Preterm birth prevention in singleton with short cervix; in twins limited evidence but considered for short cervix; not for routine multifetal use

Aspirin (pre-eclampsia prevention)^[1]

Antiplatelet (low-dose)

All twin pregnancies have elevated pre-eclampsia risk and qualify for prophylaxis

Reduced fetal movements in either twin at any gestation — same-day maternity assessment unit; this is harder to detect than in singletons^[1]
Sudden weight gain (>2 kg/week), severe leg/face swelling, severe headache or visual change — pre-eclampsia signs warrant same-day review^[1]
Attend every growth scan and Doppler appointment; many complications in monochorionic twins are silent and progress quickly^[1]

All monochorionic twin pregnanciesTertiary fetal medicine for chorionicity-specific surveillance^[1]
Suspected TTTS, sIUGR, or selective fetal anomalyTertiary fetal medicine same-week for fetoscopic options^[1]
Threatened preterm labour or short cervixObstetric admission for steroid and consideration of progesterone, cerclage, or transfer to neonatal-equipped centre^[1]
Higher-order multiples (triplets+)Tertiary maternal-fetal medicine and consider multifetal reduction counselling per local framework^[1]

Antenatal surveillance, preterm birth prevention, and timing of delivery for twin and higher-order multiple pregnancies stratified by chorionicity.

1.FOGSI-ICOG Good Clinical Practice Recommendations on Multifetal Pregnancy Management (2024); ISUOG Multiple Pregnancy Practice Guideline; NICE NG137 (2024)