How Obesity Affects a Woman’s Fertility

Many studies have come to the same conclusion; being obese affects a woman’s ability to fall pregnant. Many women who are obese and are having trouble conceiving will often hear from their doctors that if they lose weight, they will have a higher likelihood of falling pregnant.

Obesity often causes other health problem so that even if the extra weight on the body is not the cause of the fertility issues, the other health problems may become factors in reducing the likelihood of conception for women who are obese.

While losing weight does not improve a woman’s fertility, her sexual function does, say Penn State College of Medicine researchers, who reported their findings in the Journal of Clinical Endocrinology and Metabolism.

Richard Legro, M.D. explained that obese women have problems ovulating, which affects fertility. “Obesity, especially centered in the abdomen, among infertile women seeking pregnancy is also associated with poor response to ovulation induction and with decreased pregnancy rates.”

Doctors usually tell obese women who want to get pregnant to lose weight. Dr. Legro and team set out to determine what impact gastric bypass surgery might have on women’s reproductive function.

As a large amount of weight is lost after bariatric surgery in a short period, the team thought this would be a good way to examine the effects of weight loss on reproductive function in women. Each patient can be observed while they are obese and after undergoing surgery to identify any changes.

The study involved 29 morbidly obese women. An obese person has a BMI (body mass index) of 30 or more, while a morbidly obese individual’s BMI is 40 or more. People who are morbidly obese have accumulated so much body fat that it may have an adverse effect on their health. All the women were of reproductive age. They were followed for two years after Roux en Y gastric bariatric bypass surgery.

The researchers collected daily urine samples over the course of a menstrual cycle to determine ovulation frequency and quality. They were surprised to find that ovulation rates stayed high – over 90% during all their checks before surgery, and then afterwards at 1, 3, 6, 12 and 24 months.

There was no change in the quality of ovulation. Losing weight did not have a significant effect on the ovarian cycle.

They did find a notable shortening of eight to nine days during the follicular phase. The follicular phase is the period from the end of the previous menstrual flow up to ovulation (when the egg is released). Within three months, after surgery, the follicular phase was found to be 6.5 days shorter, and then at 24 months 9 days shorter.

Obese women tend to have longer menstrual cycles because their follicular phase is longer. Nobody knows why this phase shortens when an obese woman loses weight.

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