Kristi Maas1, Ekaterina Galkina2, Kim Thornton1, Alan S Penzias1, Denny Sakkas3. 1. Boston IVF, 130 Second Avenue, Waltham, MA 02451, USA Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA. 2. Department of Computer Science, University of Massachusetts, Lowell, MA, USA. 3. Boston IVF, 130 Second Avenue, Waltham, MA 02451, USA dsakkas@bostonivf.com.
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 INTERESTS: No funding was received for this study. The authors have no conflicting interests. TRIAL REGISTRATION NUMBER: Not applicable.
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 INTERESTS: No funding was received for this study. The authors have no conflicting interests. TRIAL REGISTRATION NUMBER: Not applicable.
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