Double vitrification-warming cycles, coupled with blastocyst biopsy, impair live birth but do not affect neonatal...

To identify whether the transfer of blastocysts that have been vitrified, thawed, biopsied, revitrified, and subsequently rethawed affects clinical outcome and neonatal outcome.

A retrospective study was conducted in a single assisted reproduction technology center from September 2016 to March 2021. Women undergoing single frozen euploid blastocysts transfer were stratified into two groups based on number of vitrification-thawing cycles: single vitrification coupled with single biopsy (group A, n = 177) and double vitrification coupled with single biopsy (group B, n = 30). Pregnancy and perinatal outcomes of the two groups were compared.

Clinical pregnancy rates were similar between the two groups. Group B was associated with an increased likelihood of live birth when compared with group A by different multivariable analysis models (model 1: odds ratio, 0.42 [95% confidence interval, 0.18-0.97], P = 0.041; model 2: odds ratio, 0.38 [95% confidence interval, 0.16-0.92], P = 0.033). No major obstetrical complication was reported in the two groups and only one malformation live birth was reported in group A.

The procedure of double vitrification-warming cycles, coupled with single biopsy, increases pregnancy loss and ultimately diminishes live birth but does not affect perinatal outcome. Future studies with a larger sample size would help to validate the results.