P15.10: Embryo reduction in trichorionic triplets: effect on time to delivery and birthweight discordance

Abstract

The aim of the study was to assess the effects of embryo reduction (ER) in trichorionic triplet pregnancies on the gestational age (GA) at delivery and the intertwin birthweight (BW) discordance. This was a retrospective cohort study. ER was performed before 16 weeks' gestation in all pregnancies via the transabdominal approach. Dichorionic, as well as monochorionic, triplets and triplet pregnancies reduced to one embryo were excluded from analysis. We compared the GA at delivery and the prevalence of intertwin BW discordance greater than 20% in trichorionic triplet pregnancies reduced to twins with primary dichorionic twins. We identified 52 reduced trichorionic triplet pregnancies which underwent ER and 226 primary dichorionic twin pregnancies. The procedure-related fetal loss rate was 1.9%. Reduced twin pregnancies had significantly lower GA at delivery than the primary twins (median 34.0, IQR 31.0-36.71 vs 36.71, IQR 34.71-37.57 weeks; p<0.001). Stratified according to the GA at delivery, reduced twins had an increased rate of preterm birth below 24 weeks [OR: 7.23 (95%CI: 1.96 to 26.69), P=0.003], between 24 and 28 weeks [OR: 4.38 (95%CI: 1.60 to 11.99), P=0.005], between 28 and 34 weeks [OR: 2.44 (95%CI: 1.29 to 4.63),P=0.007], and before 34 weeks' gestation [OR: 5.44 (95%CI: 2.84 to 10.42),P<0.001]. There were no significant difference between reduced and primary dichorionic twins regarding BW discordance >20% (15.3% vs. 18.1%, respectively P=0.61). Embryo reduction is not associated with increased incidence of BW discordance, but is associated with delivery on an average 2-3 weeks earlier when compared to the primary dichorionic twins.