Maternal body mass index is not associated with assisted reproductive technology outcomes.

The effects of body mass index (BMI) on assisted reproductive technology (ART) outcomes such as ovarian dysfunction, poor ovum quality, and endometrial dysfunction have been studied; however, many aspects remain controversial. Therefore, we retrospectively investigated the relationship between BMI and ART outcomes. For 14,605 oocyte retrieval cycles at our hospital between January 2016 and December 2020, BMI was divided into five groups (< 18.5, 18.5-20.0, 20.0-22.5, 22.5-25.0, ≥ 25 kg/m) and measured before oocyte retrieval. The normal fertilization and high-grade blastocyst rates were compared. In addition, in the 7,122 frozen-thawed embryo transfers (FET) with highest-grade embryos, the clinical pregnancy, miscarriage, and live birth rates were investigated in the five BMI groups. Multiple regression analysis on normal fertilization and high-grade blastocyst rates revealed no statistically significant differences. Furthermore, after propensity score matching on FET, there was no significant difference in clinical pregnancy, miscarriage, and live birth rates in the BMI groups. BMI is a risk factor for complications during pregnancy; however, it does not affect ART outcomes. Therefore, we believe weight guidance should be provided to women with obesity at the start of infertility treatment, but treatment should not be delayed.