Triplet Pregnancy

Triplet pregnancy is a pregnancy with three fetuses, arising from three eggs, or from one egg that splits and another that does not, or from a single egg that splits twice. It is far commoner after fertility treatment. It matters because delivery is usually preterm, and the risks of preterm birth, cerebral palsy, anaemia, preeclampsia and postpartum haemorrhage are much higher than for twins.

• Risk factors: ovulation induction, assisted conception with multiple embryo transfer, advanced maternal age, family history.
• Chorionicity (trichorionic, dichorionic or monochorionic components) decides surveillance.
• Fetal reduction to twins can be offered at 11 to 13 weeks.

Women have rapid uterine growth, severe nausea, tiredness, breathlessness, swelling, backache and heartburn, with the uterus much larger than dates. Examination may find many fetal parts.

• Fundal height 6 or more cm above dates by 20 weeks.
• Marked anaemia and swelling.
• Differential diagnosis: twin pregnancy, polyhydramnios, molar pregnancy, large fibroid, ovarian mass.
• Complications: preterm labour, preeclampsia, anaemia, gestational diabetes, growth restriction, discordance, twin to twin transfusion in monochorionic components, cord complications, malpresentation, postpartum haemorrhage, cerebral palsy, stillbirth.

The approach is ultrasound at 11 to 13 weeks to define chorionicity and amnionicity, and a close schedule of scans.

• Ultrasound at 11 to 13 weeks: number of placentas and sacs, crown rump length, nuchal translucency, label the fetuses; check for T and lambda signs.
• Scans every 4 weeks for trichorionic and every 2 weeks from 16 weeks for any monochorionic component; cervical length at 18 to 22 weeks.
• Full blood count at booking, 20 and 28 weeks; 75 g oral glucose tolerance test at 24 to 28 weeks; blood pressure and urine protein every visit.
• Anomaly scan with fetal echocardiography at 20 to 22 weeks.

The principle is intensive antenatal care in a referral unit, fetal reduction counselling, prevention of preeclampsia and delivery by caesarean section at 32 to 34 weeks.

• Supportive: review every 2 weeks; a diet of 3000 kcal daily with protein; rest from 24 weeks; admission from 24 to 28 weeks if the cervix shortens or contractions occur; counselling on risks and fetal reduction at 11 to 13 weeks; birth in a unit with neonatal intensive care and three neonatal teams.
• Pharmacological: folic acid 400 micrograms oral daily; ferrous sulphate 200 mg oral 8-hourly; aspirin 150 mg oral at night from 12 weeks to 36 weeks; calcium 1.5 g elemental oral daily where intake is low; betamethasone 12 mg IM twice, 24 hours apart, from 24 weeks to 34 weeks and 6 days; magnesium sulphate 4 g IV over 20 minutes then 1 g per hour until delivery for 24 hours at most before 32 weeks; nifedipine 20 mg oral once then 10 to 20 mg every 6 to 8 hours for up to 48 hours for contractions; cefazolin 2 g IV before caesarean section; oxytocin 10 IU IM at birth then infusion of 20 IU in 1 litre sodium chloride 0.9 percent at 125 mL per hour for 4 hours; carboprost 250 micrograms IM every 15 minutes (maximum 8 doses) for atony, avoided in asthma.
• Procedures: multifetal reduction to twins at 11 to 13 weeks by a fetal medicine team under ultrasound guidance; planned caesarean section at 32 to 34 weeks (36 weeks for trichorionic if the pregnancy is uncomplicated); balloon tamponade, compression sutures or hysterectomy for uncontrolled haemorrhage.
• Special groups: monochorionic components need fortnightly Doppler scans, with laser treatment for twin to twin transfusion and selective reduction for other complications.
• Red flags: contractions, short cervix below 25 mm, leaking fluid, blood pressure 140/90 mmHg or more, bleeding, rapid abdominal growth, reduced movements of any fetus.
• Follow-up: growth scans every 2 weeks from 24 weeks; postnatal haemoglobin at 24 hours; ferrous sulphate 200 mg oral 8-hourly for 3 months; contraception and counselling on future pregnancy.