Clinical outcomes in higher-order multiples reduced to dichorionic diamniotic (DCDA) twins compared with primary twins and singletons: A prospective observational study

OBJECTIVE

To compare outcomes in higher-order multiple pregnancies reduced to dichorionic diamniotic (DCDA) twins with primary DCDA twins and singleton pregnancies.

METHODS

This prospective observational study included all higher-order multiple pregnancies that underwent ultrasound-guided transabdominal fetal reduction at 11-13 weeks of gestation from January 2018 to June 2020. Outcomes were compared with 100 primary DCDA twins and 1078 singletons.

RESULTS

Sixty-four higher-order multiples underwent reduction at mean gestational age of 11.46 weeks. Of the reduced pregnancies, 3.12% resulted in miscarriage before 24 weeks compared with 2% (2/100) of primary twins and 0.74% of singletons (P = 0.09). The mean gestational age at delivery was 33.48 weeks for reduced twins, 34.52 weeks for primary twins (P = 0.10) and 38.14 weeks for singletons (P < 0.001). Compared with primary twins, the adjusted odds of preterm delivery before 34 weeks and before 36 weeks for reduced twins were 0.56 (95% confidence interval [CI] 0.48-3.54, P = 0.62) and 0.84 (95% CI 0.78-8.85, P = 0.08), respectively. There was no significant difference in rates of pre-eclampsia, Cesarean delivery, birth weight below the 10th and 3rd centiles, and perinatal mortality among primary and reduced twins. All risks were significantly lower in singleton pregnancies.

CONCLUSION

Reduced twins have similar obstetric and perinatal outcomes as primary twins, but adverse outcomes are significantly higher in both groups when compared with singleton pregnancies.