Twins: DCDA (Dichorionic)

In DCDA twins, 'dichorionic' means two chorions (placentas) and 'diamniotic' means two amniotic sacs. On an early ultrasound (before 14 weeks), we identify this by the 'Lambda sign'—a thick triangular wedge of placental tissue where the two sacs meet. Because each baby has its own 'kitchen' (placenta), if one baby has a growth issue, it rarely affects the blood supply or safety of the other baby.

While safer than shared-placenta twins, DCDA pregnancies carry higher risks than singletons:

• Premature Birth: Twins are more likely to be born before 37 weeks due to uterine stretching.
• Fetal Growth Restriction: One or both babies may grow smaller than average because the uterus is crowded.
• Pre-eclampsia: The risk is 2-3 times higher than in a singleton pregnancy.
• Gestational Diabetes: More common due to the increased placental hormones.

The most critical step is the 12-week dating scan:

1. Chorionicity Check: Confirming the separate placentas is essential for planning the rest of your care.
2. Aneuploidy Screening: Twins can have NIPT or combined screening, although we must interpret results for each baby individually.
3. Cervical Length: Monitoring the cervix in the second trimester to predict the risk of early delivery.

We follow a structured surveillance program:

• Monthly Growth Scans: From 24 weeks onwards, we scan every 4 weeks to measure each baby and check their fluid levels.
• Maternal Screenings: Frequent blood pressure and urine checks at every visit.
• Aspirin: We usually recommend low-dose aspirin to reduce the increased risk of pre-eclampsia.
• Nutrition: Higher requirements for iron, folic acid, and calcium.

Outcomes for DCDA twins are generally excellent:

• Survival: Over 98% of DCDA twins are born healthy and at a safe gestational age.
• Timing of Birth: We typically aim for delivery at 37 to 38 weeks. Waiting longer does not usually benefit the babies and can increase the risk of placental failure.
• Mode of Delivery: Many DCDA twins can be delivered vaginally if the first baby is head-down. C-sections are reserved for specific medical indications.

If you find out you are having twins, you should seek care at a specialized center that understands twin-specific growth charts and management.

Dr. Leanne Bricker leads our multiple pregnancy service. We provide a supportive environment where you can receive the specialized imaging and clinical expertise needed for a successful DCDA twin journey.