The effects of oocyte donor and recipient body mass index on live birth rates and pregnancy outcomes following assisted reproduction

OBJECTIVE: To investigate the effects of oocyte donor and recipient body mass index (BMI) on outcomes of vitrified donor oocyte assisted reproductive technology (ART). DESIGN: Retrospective cohort study. SETTING: Private fertility center. PATIENT(S): A total of 338 oocyte donors and 932 recipients who underwent 1,651 embryo transfer cycles in 2008–2015. INTERVENTION(S): Multivariable log binomial regression models with cluster-weighted generalized estimating equations were used to estimate the adjusted risk ratios. MAIN OUTCOME MEASURE(S): Live birth, defined as the delivery of at least one live-born infant, including all embryo transfer cycles. Secondary outcomes included birth weight and gestational length only among singleton live births. RESULTS: The mean ± SD body mass indexes (BMIs) of donors and recipients were 22.6 ± 2.5 kg/m(2) and 24.6 ± 4.8 kg/m(2), respectively. There were no significant associations between donor BMI and probability of live birth. Recipients with BMI ≥35 kg/m(2) had a significantly higher probability of live birth compared with normal-weight recipients. Among singleton live births, recipients with BMI <18.5 kg/m(2) had a lower risk whereas women with BMI ≥35 kg/m(2) had a higher risk of delivery in an earlier gestational week compared with normal weight women. Recipients with a BMI ≥35 kg/m(2) also had a higher risk of having a low birth weight infant compared with normal-weight women. CONCLUSIONS: In the setting of vitrified donor oocyte ART, recipient BMI was positively associated with probability of live birth but negatively associated with gestational length and birth weight among singleton births.