Congenital anomalies and perinatal outcomes following blastocyst vs cleavage-stage embryo transfer: systematic review and network meta-analysis.

Current very low-certainty evidence shows that there may be little to no difference in the risk for congenital anomalies or adverse perinatal outcomes of pregnancies resulting from blastocyst and cleavage-stage fresh/frozen embryo transfers, apart from a slightly increased probability of birth of male newborns following blastocyst transfer. When considering cryopreservation, the frozen-blastocyst group was associated with a reduction in the risk for LBW compared to both fresh groups, and the fresh-cleavage with a reduction in the risk for perinatal death compared to both blastocyst groups. High-quality RCTs with separate data on fresh and frozen cycles and consistent reporting of culture conditions and freezing methods are mandatory. Individual participant data meta-analyses are required to address the substantial inconsistency resulting from current aggregate-data approaches. This article is protected by copyright. All rights reserved.