Multifetal Pregnancy Reduction is a technique used to reduce the fetal number with the goal of mitigating risks of adverse outcomes associated with multiple gestations. Monochorionic diamniotic twin pregnancies are subject to unique complications, contributing to adverse pregnancy outcomes. Thus, patients have an option to electively reduce one fetus with the goal of improving outcomes.
Our objective was to compare outcomes of elective reduction of monochorionic diamniotic twins by radiofrequency ablation to planned ongoing monochorionic diamniotic twins.
We performed a retrospective review of 315 monochorionic diamniotic twin gestations that underwent first-trimester ultrasound within one institution. Planned electively reduced twins were compared with ongoing monochorionic diamniotic twins. All reductions were performed via radiofrequency ablation of the cord insertion site into the fetal abdomen. The primary outcome was preterm birth less than 36 weeks. Secondary outcomes included gestational age at delivery, preterm birth less than 37, 34, 32, and 28 weeks, unintended loss, and adverse perinatal outcomes.
Among 315 monochorionic diamniotic pregnancies, 14 (4.4%) underwent elective multifetal pregnancy reduction and 301 (95.6%) were planned ongoing twins. The mean GA of RFA in the elective MPR group was 15.1 ± 0.68 weeks. Patients who underwent elective multifetal pregnancy reduction had significantly higher maternal age (p<0.01) and were more likely to be Asian (p<0.01). They were also more likely to have undergone in vitro fertilization (p=0.03) and chorionic villus sampling (p<0.01). There was a significantly higher rate of term deliveries in the elective radiofrequency ablation group compared to ongoing twins (GA 38 weeks (IQR, 36.1, 39.1) vs. 35.9 weeks (IQR, 34, 36.9), (p<0.01)). Patients with ongoing pregnancies had a trend of increased rate of preterm birth less than 36 weeks (OR 3.4, 95% CI 1.0-12.0; p=0.06), a significantly increased risk of preterm birth less than 37 weeks (OR 8.0, 95% CI 2.4-26.4; p<0.01), and no difference less than 34, 32, or 28 weeks. All patients who underwent elective radiofrequency ablation had successful pregnancies with no pregnancy losses or terminations. Of ongoing gestations, 36 required procedures including 16 (5.3%) medically-indicated radiofrequency ablation, 14 (4.6%) laser ablation, and six (1.9%) amnioreductions. Twenty-two patients (7.3%) with planned ongoing twins had total pregnancy loss less than 24 weeks. Twelve (4.0%) had unintended loss of one fetus before 24 weeks in the ongoing pregnancy cohort and 12 (4.0%) had unintended loss of both fetuses before 24 weeks. Five patients (1.7%) in the ongoing pregnancy group had intrauterine fetal demise greater than 24 weeks and 10 patients (3.3%) electively terminated both fetuses. There was no significant difference in loss rates between the two groups.
In this study of monochorionic diamniotic twins, patients who elected to undergo multifetal pregnancy reduction had significantly lower rates of preterm birth less than 37 weeks and a lower trend of preterm birth less than 36 weeks without an increased risk of pregnancy loss. Median gestational age at delivery was significantly higher at 38 weeks in the elective multifetal pregnancy reduction group, as compared to 35.9 weeks in the ongoing pregnancy group. Further research is needed to clarify if multifetal pregnancy reduction improves long-term outcomes.

Copyright © 2021. Published by Elsevier Inc.