Do day-3 embryo grade predict day-5 blastocyst transfer outcomes in patients with good prognosis?

The main aim was to investigate whether or not day-3 embryo grade could predict day-5 blastocyst transfer outcomes in patients with good prognosis. This study included 233 elective single blastocyst transfers (eSBT) by D5 selection with conventional morphology (CM) and 121 elective single blastocyst transfers (eSBT) by D5 selection with time-lapse monitoring system (TL) from October 2016 to October 2017. All the patients were submitted to controlled ovarian stimulation (COS) with long-term protocol and transferred for the first time. The main outcome measures were clinical pregnancy rates (CPR) and ongoing pregnancy (OPR). Our results suggested that CPR (58.04 versus 57.89 versus 55.56%; p = .957) and OPR (66.07 versus 65.79 versus 64.44%; p = .981) were comparable among day 3 grades I, grades II, and grades III groups. We also observed that the TL group showed a slightly better CPR and OPR than CM group (p > .05). Our findings suggested that good or poor embryos at day-3 were not predictive of the outcomes of good-quality blastocysts in a good-prognosis population. It needed to be emphasized that time-lapse monitoring might be useful for elective single blastocyst transfer.