Obstetrics and perinatal outcomes between elective single versus double blastocyst transfer in women younger than 35 years: A cross-sectional study.

Introduction: Clinicians have a positive attitude towards multiple embryo transfer in in vitro fertilization (IVF) cycles, considering increased live birth rates compared to single embryo transfer. We aimed to evaluate obstetric and perinatal outcomes among young women who became clinically pregnant after single & double blastocyst transfer.

Material-method: 545 women under 35 years who became clinically pregnant after fresh blastocyst transfer was evaluated retrospectively. The participants were dividedaccording to the transferred embryo number - the elective single blastocyst transfer group (eSBT) (n=112) and the double blastocyst transfer group (DBT group) (n=433). Obstetric and perinatal outcomes were recorded.

Results: Live birth and abortion rates per pregnancy and per gestational sac, having a fetus with congenital anomaly per pregnancy and per neonate, and gestational complications were comparable between the groups. Multiple pregnancy, Cesarean section, and admission to neonatal intensive care unit (NICU) and hospitalization day in NICU per neonate were higher in the DBT group than in the eSBT group. Mean gestational week, birth weight, birth height decreased with the embryo transfer number.

Conclusion: DBT transfer appears to be associated with increased multiple pregnancies, Cesarean section, prematurity, decreased fetal anthropometric measurements, and admission to NICU without an increase in live birth and abortion rates. Therefore, it will be easier for clinicians to choose eSBT by providing young couples undergoing IVF treatment with detailed information about multiple pregnancies and prematurity.