Validity for assisted hatching on pregnancy rate in assisted reproductive technology: Analysis based on results of Japan Assisted Reproductive Technology Registry System 2010

The aim of this study was to assess the efficacy of assisted hatching (AH) in assisted reproductive technology (ART) treatment.In this retrospective observational study, the data of patients who were registered in the National ART Registry System of Japan between January and December 2010 were analyzed. The descriptive statistics and validity of AH in fresh embryo transfer (ET) and frozen-thawed ET were assessed by using multiple logistic regression analyses.From a total of 105,450 single ET, 46,029 (43.7%) cycles underwent AH. A total of 9737 (21.3%) and 36,292 (60.9%) cycles underwent AH from 45,818 fresh single ET and 59,632 frozen-thawed single ET, respectively. In the fresh ET patients that underwent AH, the clinical pregnancy and live birth rate were significantly decreased in patients of all ages compared with that of the non-AH group. In the frozen-thawed ET patients, there was no significant difference in pregnancy and live birth rate between the AH group and the non-AH group.AH treatment was more frequently performed in frozen-thawed ET patients than in fresh ET patients, and in the blastocyst stage than in the early cleavage stage. A significantly decreased pregnancy and live birth rate was observed in the fresh ET patients who underwent AH. In the frozen-thawed ET patients who underwent AH, improvement in the clinical pregnancy and live birth rate was not observed. Further studies on the indication and application of AH in ART treatment are required.