No change in live birthweight of IVF singleton deliveries over an 18-year period despite significant clinical and laboratory changes

Abstract

Study question: Has live birthweight changed over 18 years of autologous fresh and frozen IVF? summary answer: Regardless of changes in clinical care and laboratory practice over 18 years, birthweight has remained stable. what is known already: Birthweight has historically been used as a marker of neonatal health. Frozen embryo transfers lead to heavier live birthweights compared with fresh embryo transfers. study design, size, duration: This retrospective cohort study included 7295 singletons from autologous fresh (n = 6265) and frozen (n = 1030) IVF cycles from 1996 to 2013. participants/materials, setting,methods: All patients undergoing autologous IVF cycles between 1996 and 2013 resulting in a singleton live born with a birthweight recorded were included. One-way ANOVA and t-tests compared mean live birthweight in fresh and frozen cycles in 6-month increments over 18 years. Linear regression analysis was performed to investigate predictors of birthweight. main results and the role of chance: Mean birthweight after fresh (3283±601 g) and frozen (3462±621 g) cycles were significantly different (P < 0.001). ANOVA demonstrated no significant difference in mean weight from fresh or frozen cycles over 6-month intervals. No difference in weight was noted between Days 3 and 5 transfers or between ICSI and standard IVF. No difference was found across known changes when comparing media, laboratory location, cryopreservation method or gonadotrophins. limitations, reasons for caution: Limitations include the small number of frozen low birthweight neonates. wider implications of the findings: Our study suggests that changes in IVF practice, with the exception of fresh or frozen embryo transfer, have little impact on mean live birthweight. study funding/competing interest(s): No funding was received for this study. The authors have no conflicting interests. trial registration number: Not applicable.