Extended embryo culture is not associated with increased adverse obstetric or perinatal outcome

Objective We sought to compare obstetric and perinatal outcomes of singletons born after extended embryo culture and a single blastocyst stage embryo vs a single cleavage stage embryo transfer. Study Design This was a retrospective cohort study of 1543 fresh single embryo transfers using nondonor oocytes in women 40 years old from December 2008 through December 2012 at the reproductive unit of McGill University Health Center. The main outcome measures were perinatal outcomes including birthweight, low birthweight, small for gestational age, preterm delivery, preeclampsia, placental abruption, and neonatal complications. Covariates were maternal age, body mass index, smoking, cause of infertility, parity, and sex of the baby. Results Transfers of 693 fresh single cleavage embryos and 850 fresh single blastocysts resulting in 564 pregnancies and 381 singleton deliveries were analyzed. Blastocyst transfer resulted in a higher clinical pregnancy rate (50.1% and 19.9%) and live birth rate (33.5% and 13.8%) compared to cleavage embryo transfer, respectively (P001). Multivariate analyses for pregnancy revealed no increased risk of maternal or neonatal complications in pregnancies resulting from extended embryo culture. Conclusion Live births resulting from extended embryo culture and a single blastocyst transfer are not associated with increased adverse obstetric and perinatal outcome compared to live births from a single cleavage embryo transfer in women 40 years old.