P–784 Neonatal follow-up of babies born derived from mono-pronuclear zygotes

Abstract

Abstract Study question Are the neonatal outcomes normal of babies derived from the transfer of blastocysts derived from mono-pronuclear(1PN) zygotes? Summary answer There was no effect on growth or increase in congenital anomalies up to 18-months in babies of 1PN-derived births. What is known already 1PN zygotes are observed in ART, albeit at a low rate. We have previously reported that 80.7% of 1PN zygotes derived from IVF or ICSI had a biparental chromosome using Live Cell imaging techniques, and some of these developed to the blastocyst stage (Tokoro et al. ASRM 2013). Furthermore, we have reported that these blastocysts can result in a viable pregnancy and healthy live birth (Tsuji et al. ASRM2020). However, there is some uncertainty about the developmental mechanism of 1PN zygotes, and there is no clear consensus on their clinical utility. Study design, size, duration This was a retrospective study which included 55 cases where there was a live birth after single embryo transfer of a blastocyst derived from 1PN zygote. The incidence of birth defects, birth weight was recorded as well as a physical development survey of 25 children who responded to the 18-months follow-up survey. The time period was 72 months (January 2013 to December 2018). Participants/materials, setting, methods Patients seeking fertility treatment at an established private IVF clinic. We compared the birth weight, birth after18-months height and weight of children born to 1PN zygotes with data from a control, 2PN group. Statistical significance was determined using the t-test (level of P < 0.05). Main results and the role of chance The incidence of birth defects in 1PN embryo-derived infants was 1.8% (1/55). The average birth weight of boys in the 1PN group was 3105.6+/–360.3g, which was not significantly different from 3041.0+/–443.3 g in the 2PN group. In girls, the average birth weight was 3085.7+/–454.9 g in the 1PN group, which was not significantly different from the 2PN group (2938.9+/–311.5 g). The average height at 18-months, was 81.6+/–2.5 cm vs 80.5+/–3.4 cm for boys; 79.0+/–1.8 cm vs 79.0+/–3.4 cm for girls in the 1PN and 2PN groups, respectively. The average body weights of the 1PN and 2PN groups were 11.1+/–1.1 kg vs 10.7+/–1.1 kg for boys; 9.7+/–0.9 kg vs 10.1+/–1.0 kg for girls, respectively. There was no significant difference in average height and weight up-to the 18-months follow-up survey. Limitations, reasons for caution The incidence of 1PN derived births is low and the study was limited to cases of single blastocyst embryo transfer. Wider implications of the findings: The incidence of congenital anomalies in Japan was around 1.7 to 2%, and the incidence was similar in the 1PN. There was no difference in the birth weight and 18-months follow-up survey of the 1PN compared with the 2PN. We have demonstrated that there is clinical utility of 1PN embryo. Trial registration number Not applicable