Does obesity make a woman less fertile?

No, according to a recent study of over 500 first cycle recipients of donor oocytes. Obese recipients do not have significantly lower rates of implantation or pregnancy or significantly higher rates of spontaneous abortions than women who are underweight, overweight (but not obese), or of normal weight.

Previous studies have found connections between maternal obesity and reduced fertility, lower live birth rates after IVF and intracytoplasmic sperm injections, and lower rates of pregnancy and implantation after ART. Other studies have linked obesity to insufficient follicle development, a lower oocyte count, and an increased requirement for gonadotropins.

But the authors of the current study claim that most of those reports looked at obesity's effect on ovarian function, not on endometrial receptivity. They say the current study excludes obesity's effects on ovarian follicular maturation and focuses instead on its effects on the endometrium, which appear to be nil.