A new study from the National Institutes of Health looked at 501 couples from Michigan and Texas from 2005 to 2009 who were trying to get pregnant. It had the women chart their monthly cycles, intercourse and results of home pregnancy tests.
It also looked at the body mass index of the couples and compared non-obese women and men to the most obese men and women in the study who had a BMI of 35 or greater. What it found was that it took the obese couples 59 percent longer to get pregnant.
The study proved what fertility doctors were experiencing in their offices.
We talked to two fertility doctors, brothers Parviz Kavoussi, who specializes in male infertility, and Shahryar Kavoussi, who specializes in female infertility, both at Austin Fertility & Reproductive Medicine, about why obesity would affect fertility.
It’s often about the hormone levels and what extra fat does to those levels, they say. In men, a hormone imbalance can cause more testosterone to be converted to estrogen and fat. “The more that’s converted, the more it’s bad for sperm production and function,” Parviz Kavoussi says.
The other problem is that the excess fat, especially around the abdomen, might cause the testicles to be too warm. Testicles need to be 2 to 4 degrees cooler than the rest of the body for good sperm production.
In women, the problem is the estrogen to androgen ratio. That ratio has to be correct in order for a woman to ovulate. Those hormones don’t even have to be imbalanced for less ovulation, says Shahryar Kavoussi. “Just because they are obese, for some reason they do not achieve pregnancy.” More research needs to be done on why that is.
The Kavoussis like to look at the whole health picture in their patients. Is there a reason for the extra weight such as a hormone imbalance, which also might be causing the infertility? Can they solve that problem and by doing so increase fertility?
If it’s not something easily correctable with hormone replacements and more about lifestyle, then the Kavoussis would counsel their patients to work on that and give them time to lose the weight and be the healthiest they can be in order to get pregnant and have a healthy pregnancy.
“It’s better to have a healthier lifestyle and try to lose weight through diet and exercise,” Shahryar Kavoussi says, but he’s also very aware that the decision to lose weight is very personal.
In women who are older, though, waiting to lose weight might not be a good thing. “We don’t have time to take three months to six months for her to lose weight,” Shahryar Kavoussi says. “Time can take a toll on eggs.”
The study proves what the Kavoussis already knew, but more needs to be known about why obesity and infertility are linked and what can be done beyond improving hormone levels and beyond losing weight.