Abstract: Obesity causes the ovulation disorder, difficulty conceiving naturally and infertility. With the incidence of infertility in obese women increasing, the number of people seeking assisted reproductive technology is also rising. Obesity increases the days and doses of Gn, decreases the number of eggs obtained, and reduces the clinical pregnancy rate and live birth rate. Obesity affects oocyte quality, preimplantation embryo quality and endometrial receptivity. Obesity affects oocyte quality by altering follicular fluid metabolites and gene expression, increasing lipotoxicity and adiponectin, and intervening telomere morphology. The model of diet induced obesity (DIO) showed that the delayed development of oocyte and the change of cell composition affected the quality of embryo. Animal models showed that obesity impaired endometrial decidualization. The endometrial receptivity array (ERA) and sequence analysis showed that the abnormal gene expression in endometrium of implantation window affected endometrial receptivity. Obese pregnancies increase the risk of obstetric complications. Obesity in mothers increases the risk of metabolic disorders in multigenerations, which is an intergenerational effect. Weight loss methods includes lifestyle improvement, drug intervention, surgery and so on. In clinic, obese couples are advised to lose weight timely and reasonably according to their age and ovarian reserve.

Key words: Body mass index, Obesity, Infertility, female, Reproductive techniques, assisted, Fertility, Pregnancy outcom