Nonpronuclear- and Monopronuclear-derived Blastocysts Do Not Impair Subsequent Perinatal and Maternal Outcomes

The routine clinical practice is to prioritize the transfer of blastocysts derived from 2 pronuclei (2PN) embryos if they are available. For women who only have blastocysts resulting from nonpronuclear (0PN) and monopronuclear (1PN) embryos, whether to transfer these embryos or discard them has been an ongoing debate over the years.

To investigate the perinatal and obstetric outcomes following the transfer of vitrified-warmed single blastocysts derived from 0PN and 1PN zygotes.

Retrospective cohort study.

University-affiliated in vitro fertilization center.

This study included singletons born to women who had undergone 0PN and 1PN vitrified-warmed single blastocyst transfers, compared to those resulting from 2PN vitrified-warmed single blastocyst transfers from 2012 to 2021.

None.

Perinatal and obstetric outcomes.

A total of 7284 women were included in the final analysis. Of these, 386, 316, and 6582 cycles resulted from 0PN-, 1PN-, and 2PN-derived blastocysts transfer, respectively. The rates of clinical pregnancy, miscarriage, and live birth were similar across the study cohorts in both unadjusted and adjusted analyses. When comparing the 0PN and 2PN groups, no differences were found in birth outcomes after adjusting for confounders. Similarly, maternal complications and mode of delivery were comparable between these 2 study cohorts. Birth parameters were also similar between the 1PN and 2PN blastocyst groups, except for more male births in the 1PN cohort. Furthermore, a comparison between the 1PN and 2PN groups did not reveal any significant differences in maternal outcomes.

The current study showed that the transfer of 0PN and 1PN blastocysts did not compromise reproductive outcomes or increase maternal and perinatal complications. This information is valuable for clinicians to counsel couples effectively and guide them in making informed decisions.