Single-embryo transfer of vitrified-warmed blastocysts yields equivalent live-birth rates and improved neonatal outcomes compared with fresh transfers

Abstract

Objective: To compare pregnancy and neonatal outcomes after fresh and vitrified-warmed single-blastocyst transfers.

Design: Retrospective study.

Setting: Private in vitro fertilization (IVF) clinic.

Patient(s): 1,209 infertile patients who underwent a total of 1,157 fresh and 645 vitrified-warmed embryo transfers.

Intervention(s): Day-5 single-blastocyst transfers using fresh or vitrified-warmed (Cryotop method) grade I and grade II embryos.

Main outcome measure(s): Fetal heart pregnancy rate, live-birth rate, gestational age, and live-birth weight.

Result(s): The overall blastocyst thaw survival rate was 94.4% and was not significantly different between blastocyst grades or developmental stages. Similar clinical outcomes were achieved for fresh and vitrified-warmed blastocyst transfers; for example, grade I blastocysts had a live-birth rate of 52.8% versus 55.3%, respectively, and grade II blastocysts had a rate of 34.9% versus 30.4%, respectively. Significantly improved neonatal outcomes were evident for vitrified-warmed blastocyst transfers for gestational age, being on average 0.3 weeks longer, and for live-birth weight with babies born on average 145 g heavier (3,296 g versus 3,441 g for fresh and vitrified-warmed groups, respectively), as compared with fresh transfers.

Conclusion(s): Embryo transfer of vitrified-warmed blastocysts yields equivalent live-birth rates and improved neonatal outcomes compared with fresh transfers.

Keywords: Assisted reproduction; blastocyst; human; single-embryo transfer; vitrification.