Birth defects after assisted reproductive technology according to the method of treatment in Japan: nationwide data between 2004 and 2012

Syuichi Ooki

The purpose of the present study was to analyze birth defects (congenital anomalies) after assisted reproductive technology (ART) according to the method of treatment, namely in vitro fertilization (IVF), intracytoplasmic sperm injection (ICSI) and frozen-thawed embryo transfer (FET). Individual lists of all ART pregnancies resulting in birth defects from birth year 2004 to 2012 presented in the annual reports by the Japan Society of Obstetrics and Gynecology were used as the initial sources of information. Relative risks (RRs) with the corresponding 95 % confidence intervals (CIs) were calculated with IVF as the reference group when calculating RR of ICSI for IVF, and with FET as the reference group when calculating the RR of fresh embryo transfer for FET. In total, 2725 stillbirths or live births with birth defects were analyzed. The prevalence of birth defects was slightly yet significantly higher in ICSI compared with IVF throughout the study period (RR = 1.15, 95 % CI 1.02-1.29) and in the 2004-2006 period (RR = 1.26, 95 % CI 1.00-1.58). The prevalence of birth defects was significantly higher for fresh embryo transfer compared with FET in the 2004-2006 period (RR = 1.39, 95 % CI 1.12-1.72). The prevalence of birth defects in multiple births was significantly lower in fresh embryo transfer compared with FET (RR = 0.70, 95 % CI 0.55-0.90, live births of 2007-2012). The present descriptive epidemiological study suggests that the impacts of different ART methods on birth defects might differ.