Fresh embryo transfer (ET) pregnancy rates are not compromised by freezing portion of embryos at 2 pronuclear (2PN) stage

Abstract

Objective: It is estimated that the cost of frozen embryo transfer (FET) is approximately a quarter of fresh IVF-ET cycle (Van Voorhis BJ et all, Fertil Steril 1995; 64:647–50). Damario et al reported high cumulative livebirth rates with embryo cryopreservation at the pronuclear stage and efficient embryo use by FET (Fertil Steril 2000; 73:767–73). Our program focused on determining optimal cumulative pregnancy rates from a single egg retrieval (ER) that could be obtained by 2 PN cryopreservation. For this study we examined clinical and cumulative pregnancy rates from our 2 PN freezing protocol.