"Vanishing Twin Syndrome"following frozen embryo transfer has no detrimental effects on offspring growth and developmental up to 3 years

Context:The current findings are restricted to short-term effects of “vanishing twin syndrome”on mother and infant health, few studies have focused on the long-term health consequences on children's growth and development. Aims:The purpose of this study was to estimate the effect of vanishing twin syndrome (VTS) on the dynamic measurement of growth and development to the singletons (0-3years) born from frozen embryo transfer(FET). Methods: This study was a retrospective cohort design and was carried from January 2017 to December 2023. To optimize statistical efficiency and reduce confounding variables, singletons conceived using VTS were matched at a 4:1 ratio based on the couple's ages, BMI, occupation, women's AMH, and embryo status, ultimately 66 children in the VTS group and 264 children in the non-VTS group were included in the final analysis. Key Results: After the propensity matching , there was no significant difference in growth and development of children between the VTS group and non-VTS group. The number of the embryo transfer in VTS group were higher than the non-VTS group(p＜0.0001).The height and the head circumference (3 months) in VTS group were lower than the non-VTS group(p＜0.05). Conclusions: The occurrence of VTS did not detrimental affect the growth and development of offspring(0-3years) from FET. Implications: More reasonable, comprehensive and long-term follow-up results are needed for further verification. More than one embryo transfer not only increases the rate of multiple births, but also increases the occurrence of VTS in assisted reproductive technology(ART).