Risk of major congenital anomalies after assisted hatching: analysis of three-year data from the national assisted reproduction registry in Japan

ObjectiveTo assess perinatal risk of major congenital anomalies in children born after embryo transfer with assisted hatching (AH).DesignRetrospective cohort study.SettingNot applicable.Patient(s)Cycles registered from 2010 to 2012 and conceived via single-embryo transfer were included for the analysis. Live births, still births after 22 weeks of gestation, and selectively terminated cases because of congenital anomalies were included.Intervention(s)None.Main Outcome Measure(s)Major congenital anomaly.Result(s)AH was performed in 35,488 cycles among 72,125 included cycles (49.2%). A total of 1,046 major congenital anomalies (1.4%) were identified (1.36% in AH group vs. 1.50% in non-AH group). Overall risks for major congenital anomalies were not significantly different between AH and non-AH groups adjusting for maternal age, calendar year, fetal sex, embryo stage at transfer, and status of cryopreservation. There were 1,009 cases of twins (1.5%) and 10 cases of triplets (0.015%) among all included cycles. No specific organ system demonstrated significant association between AH and non-AH groups. Subgroup analysis demonstrated no significant association between AH and non-AH groups in intracytoplasmic sperm injection cycles or in vitro fertilization in fresh cycles. Similar nonsignificant association was observed between early-cleavage or blastocyst stage at transfer in frozen-thawed cycles.Conclusion(s)Our results suggest that AH alone does not increase the risk of major congenital anomaly.