The effect of body mass index on the implantation potential of euploid embryos

Obesity has been associated with higher miscarriage rates after natural conception and IVF. However, the underlying mechanism, whether obesity affects egg quality or endometrial receptivity, is not well understood. Here we aim to determine the impact of body mass index (BMI) on the outcomes of frozen-thawed euploid embryo transfer cycles. Retrospective cohort study. Frozen-thawed embryo transfer (FET) cycles of euploid embryos between 2013 and 2017 were included. Embryos were cultured in time-lapse incubators. Preimplantation genetic testing for aneuploidy was performed using array comparative genomic hybridization or next-generation sequencing. Cycles were divided into three groups according to the female patients’ BMI: <25 kg/m2, 25-29.9 kg/m2 (overweight), and ≥ 30 kg/m2 (obese). The miscarriage rate and live birth rate (LBR) were compared between the three groups. χ2 and Fisher’s exact tests were used for categorical variables. Student’s t test and ANOVA were used for parametric data. Values were expressed as mean ± standard deviation. A total of 1011 FET of euploid embryo(s) were included: 758 with a BMI <25 kg/m2, 174 with a BMI 25-29.9 kg/m2, and 79 with a BMI ≥30 kg/m2. The women were of comparable age between the three groups (P=0.9) (Table 1). There was a trend toward a lower LBR in women with a BMI ≥30 kg/m2 compared to women with a BMI <25 kg/m2 (48.1% vs. 57.5%, respectively; P=0.1), but it did not reach statistical significance. The LBR for women with a BMI 25-29.9 kg/m2 (54%) was comparable with the other two groups (Table 1). There was no significant difference in miscarriage rates between the three groups (8.8% for BMI <25 kg/m2, 9.6% for BMI 25-29.9 kg/m2, and 11.6% for BMI ≥ 30 kg/m2; P=0.8). Overweight and obesity do not significantly affect the implantation potential of euploid embryos.Tabled 1BMI (kg/m2)<2525-29.9≥ 30P valueAge (years)36.3 ± 4.137.0 ± 4.336.7 ± 4.00.09Live birth rate (%)57.554.048.10.1Miscarriage rate (%)8.89.611.60.8 Open table in a new tab