Overweight and obesity negatively affect the outcomes of ovarian stimulation and in vitro fertilisation: a cohort study of 2628 Chinese women

Study design. A retrospective cohort study was carried out in 2222 normal weight (18.5 < BMI < 25), 379 overweight (25 < BMI < 30) and 27 obese (BMI >= 30) women who underwent their first IVF cycles between 2002 and 2008. Cycle characteristics and IVF outcomes were analysed. Results. Obese women required significantly higher dose of rFSH (3272 IU vs. 2587 IU, p < 0.001) and days of stimulation (11.89 +/- 4.57 vs. 10.42 +/- 2.03, p < 0.001), but exhibited less oocytes retrieved and significantly lower fertilisation rate (54.1% vs. 61.1%, p < 0.001) than normal weight women. Compared with normal weight women, overweight women displayed significantly less oocytes retrieved (12.98 +/- 6.91 vs. 14.49 +/- 7.96, p < 0.001), lower fertilisation rate (60.8 +/- 23.3 vs. 61.1 +/- 23.0, p < 0.001), less cleavaged embryos (7.55 +/- 4.86 vs. 8.67 +/- 5.90, p < 0.001), less high-grade embryos (4.65 +/- 3.96 vs. 5.59 +/- 4.81, p < 0.001) and cryopreserved embryos (4.44 +/- 4.55 vs. 5.49 +/- 5.55, p < 0.001). All parameters of pregnancy outcomes, including pregnancy rate, miscarriage rate and live birth rate, were comparable among three groups. Conclusions. Overweight and obesity are related with impared ovarian response, and negatively affect the outcomes of IVF.