Fetal reduction of triplet pregnancies to twins vs singletons: a meta-analysis of survival and pregnancy outcome

OBJECTIVE: This systematic review and meta-analysis aimed to compare the fetal survival rate and perinatal outcomes of triplet pregnancies after selective reduction to twin pregnancies vs singleton pregnancies. DATA SOURCES: PubMed, Web of Science, Scopus, and Embase were systematically searched from the inception of the databases to January 16, 2022. STUDY ELIGIBILITY CRITERIA: Studies comparing the survival and perinatal outcomes between reduction to twin pregnancies and reduction to singleton pregnancies were included. The primary outcomes were fetal survival, defined as a live birth at >24 weeks of gestation. The secondary outcomes were gestational age at birth, preterm birth at <32 and <34 weeks of gestation, early pregnancy loss (<24 weeks of gestation), low birthweight, and rate of neonatal demise (up to 28 days after birth). METHODS: The random-effect model was used to pool the mean differences or odds ratios and the corresponding 95% confidence intervals. To provide a range of expected effects if a new study was conducted, 95% prediction intervals were calculated for outcomes presented in >3 studies. RESULTS: Of note, 10 studies with 2543 triplet pregnancies undergoing fetal reduction, of which 2035 reduced to twin pregnancies and 508 reduced to singleton pregnancies, met the inclusion criteria. Reduction to twin pregnancies had a lower rate of fetal survival (odds ratio, 0.61; 95% confidence interval, 0.40-0.92; P=.02; 95% prediction interval, 0.36-1.03) and comparable rates of early pregnancy loss (odds ratio, 0.89; 95% confidence interval, 0.58-1.38; P=.61; 95% prediction interval, 0.54-1.48) and neonatal demise (odds ratio, 0.57; 95% confidence interval, 0.09-3.50; P=.55) than reduction to singleton pregnancies. Reduction to twin pregnancies had a significantly lower gestation age at birth (weeks) (mean difference, -2.20; 95% confidence interval, -2.80 to -1.61; P<.001; 95% prediction interval, -4.27 to - 0.14) than reduction to singleton pregnancies. Furthermore, reduction to twin pregnancies was associated with lower birthweight and greater risk of preterm birth at <32 and <34 weeks of gestation. CONCLUSION: Triplet pregnancies reduced to twin pregnancies had a lower fetal survival rate of all remaining fetuses, lower gestational age at birth, higher risk of preterm birth, and lower birthweight than triplet pregnancies reduced to singleton pregnancies; reduction to twin pregnancies vs reduction to singleton pregnancies showed no substantial difference for the rates of early pregnancy loss and neonatal death.

Automated summary

This systematic review and meta-analysis compared the fetal survival rate and perinatal outcomes of triplet pregnancies after selective reduction to twin pregnancies vs singleton pregnancies. The results showed that reduction to twin pregnancies had a lower fetal survival rate, lower gestational age at birth, higher risk of preterm birth, and lower birthweight compared to reduction to singleton pregnancies. There were no substantial differences in the rates of early pregnancy loss and neonatal death between reduction to twin pregnancies and reduction to singleton pregnancies.