Perinatal Outcomes and Determinants of Elective Embryo Reduction in Trichorionic Triplet Pregnancies

To evaluate whether elective embryo reduction (ER) reduces maternal obstetric complications in trichorionic triamniotic triplet pregnancies, to identify the maternal characteristics associated with the decision to undergo ER and its extent, and to describe associated perinatal outcomes.

This retrospective study included 120 trichorionic triamniotic triplet pregnancies managed at two tertiary hospitals in Spain (2002-2024). ER to twins or a singleton was offered before 14 weeks of gestation. Maternal characteristics, obstetric complications, and perinatal outcomes were compared between the groups.

ER was performed in 27 pregnancies (22.5%): 21 were reduced to twins and six to a singleton. ER was not associated with lower rates of preeclampsia, gestational diabetes, or intrahepatic cholestasis during pregnancy. Women undergoing ER were older, more likely to be multiparous, and less likely to have conceived using assisted reproductive technologies, although on post hoc testing only the difference in mode of conception between the two reduction subgroups remained significant after correction for multiple comparisons. Median gestational age at delivery was significantly higher after ER (36.2 and 36.6 weeks) than with expectant management (33.1 weeks; p < 0.001). Admissions for threatened preterm labor were less frequent after ER (15.0% and 16.7% vs. 42.7%; overall p = 0.033), though this difference did not remain significant after Holm correction for multiple comparisons (adjusted p = 0.068 and p = 0.791, respectively).

Elective embryo reduction did not reduce maternal obstetric complications in trichorionic triplet pregnancies, despite prolonging gestation, as previously reported. Maternal age, parity, and mode of conception were associated with the decision to undergo ER, particularly to a singleton, supporting individualized, non-directive counseling.