The Effects of Being Underweight on IVF By Michael Vermesh on February 28, 2015

It was once believed by many fertility experts that in vitro fertilization, or IVF, might be an effective means of enabling underweight women to overcome their problems with infertility. However, recent studies suggest that IVF is less effective in underweight women than it is in women who are at or near their ideal weights. In fact, even obese women have more success conceiving with IVF than underweight women.

At The Center for Fertility and Gynecology in Los Angeles, IVF and underweight patients can present clinical challenges. During consultations between our physicians and underweight patients who are interested in IVF, we advise patients of the potential obstacles faced by women who try to conceive while they are significantly below their ideal weights. Although many underweight patients are able to conceive through IVF, their chances of successful conception are less than they would be if they were at or near their ideal weights.

Recent IVF Study

A recent study of approximately 2,500 IVF cycles at a fertility clinic in Chicago found that:

Roughly 50 percent of the cycles carried out on women who were at their ideal weights or slightly above their ideal weights, as measured by body mass index (BMI), resulted in successful pregnancy and the subsequent birth of a child.
Among obese women, as measured by BMI, the rate of successful pregnancy and subsequent childbirth dropped by only 5 percent, to roughly 45 percent of the cycles carried out.
Among women who were underweight, as measured by BMI, the rate of successful pregnancy and subsequent childbirth dropped by 16 percent, to roughly 34 percent of the cycles carried out.

The results did not match the expectations of lead study author Richard Sherbahn. “Women that are too thin sometimes don’t always get periods or have irregular periods and it alters their hormonal situation,” said Sherbahn. “But that shouldn’t impact on IVF because we’re giving them hormones; we’re making them ovulate, and we’re getting eggs from them. I was kind of surprised. I didn’t expect these findings.”

The Influence of Weight on Fertility

In general, it is known that being both underweight and overweight is an infertility factor in both women and men. According to the American Society of Reproductive Medicine, the four most important factors affecting a person’s fertility are:

Whether or not he or she smokes
His or her age
Whether or not he or she has a sexually transmitted disease
Whether or not he or she is underweight or overweight

When patients who are underweight turn to us for assistance with their fertility problems, we provide a comprehensive diagnosis of the possible causes of their infertility, including their weight. We recommend weight gain as a method of improving their chances of successful conception through IVF. If a patient is unable to gain that weight, we let her know that her chances of success are somewhat lower than they might otherwise be if she were at or near her ideal weight.