Noninvasive embryo selection: kinetic analysis of female and male pronuclear development to predict embryo quality and potential to produce live birth.

Objective: To evaluate a noninvasive method of examining euploid embryos, focusing on kinetic analyses, from second polar body extrusion to pronuclear membrane breakdown (PNMBD).

Design: Retrospective embryo cohort study.

Setting: Private IVF clinic.

Patient(s): 213 frozen-thawed single blastocyst transfers.

Intervention(s): Fertilized oocytes were recorded by means of time-lapse photography, followed by kinetic analysis of female and male pronuclei (PNs).

Main Outcome Measure(s): The differences in size between the 2PNs in embryos resulting in live births compared with those of embryos from failed pregnancies were analyzed according to sequential size from early PN stages to PNMBD.

Result(s): It was found that the difference in areas between male and female PNs immediately before PNMBD is a better predictor of embryo quality if this difference is below a known cutoff value. The size of male PNs 8 hours before the onset of PNMBD should be larger than female PNs (B). The difference in size between male and female PNs 8 hours before PNMBD should be larger than the difference in their size immediately before PNMBD. When normal embryos were defined using the equation (A∪C)∩B, the birth rates for in vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI) were 68.1% and 50.0%, respectively. For the remaining embryos, defined as abnormal according to the above criteria, birth rates were 9.4% for IVF and 4.2% for ICSI.

Conclusion(s): We have developed a method for noninvasive embryo evaluation by means of the kinetic analysis of female and male PN growths. This method should enable us to select embryos that have a higher potential for healthy births.