When Kristi Caton was trying to have a baby, she knew her weight might be a problem. She has polycystic ovarian syndrome (PCOS), a disorder of the endocrine system among reproductive age women, and has always been obese. She understood weighing 238 pounds would make getting pregnant harder. After trying for a year, she visited a fertility clinic to discuss in vitro fertilization (IVF). But the clinic wouldn’t treat her because her body mass index (BMI) was 40 or higher.
“I kind of knew that it was coming. I had read about the clinic and where the numbers needed to be,” Caton, 41, of Harrisburg, Pennsylvania, told TODAY. “I was actually kind of pleased that I only needed to lose 18 pounds. I was worried they were going to say I needed to lose more than that.”
Caton lost 20 pounds and underwent a successful round of IVF. She gave birth to her son, Nicholas, on September 15, 2014. That was her first and last experience with IVF.
“We always had it in our minds we were just going to have one child,” she explained.
Does a woman's weight impact her fertility?
The New York Times Magazine published a story looking at weight and fertility and how many fertility clinics decline to treat women because of high BMIs. For women who are turned away for treatment because of their weight, it can be heartbreaking and upsetting. But there's a reason why doctors encourage women with high BMIs to lose weight: Research shows that weight plays a role in a woman’s ability to conceive.
“Overweight and obese men and women can be fertile, but it does appear that excess weight — and especially excessive abdominal fat — can increase the risk for having menstrual abnormalities that can be related to ovulation dysfunction or not releasing eggs at regular intervals,” Dr. Meredith Snook, an assistant professor in the department of obstetrics, gynecology and reproductive sciences at the University of Pittsburgh, told TODAY. “There is also evidence that obese women with regular cycles have a decreased chance of getting pregnant each month.”
When women carry excess weight they produce extra estrogen, a hormone that regulates menstrual cycles and promotes breast growth. While some estrogen is needed, too much of it can disrupt the system.
“Weight does affect menstrual cycles. It is affecting some level of the hormonal communication from the brain to the ovaries,” said Dr. Anuja Dokras, director of Penn Polycystic Ovary Syndrome Center in Philadelphia, told TODAY.
While being obese might impact fertility, doctors don’t have a target BMI that increases fertility.
“There is no magic number,” Dokras said.
Spring Gideon struggled with secondary infertility when she was trying to have another child. When her son was 2 years old, she and her husband tried to get pregnant when she weighed 290 pounds. Her periods started becoming irregular and she developed type 2 diabetes and sleep apnea.
“I would go six months without a period,” the 40-year-old from outside of Tacoma, Washington, told TODAY.
Doctors put her on progesterone to start her period, but she still didn’t ovulate. At the same time, she was unhappy about her weight and pursued bariatric surgery. As part of the prep, she lost 25 pounds. She visited the doctor and learned her surgery needed to be postponed. The reason? She was pregnant.
“We obviously weren’t doing anything to prevent it. We were all operating on the assumption that I wasn’t cycling and my hormones were out of control,” she said.
Doctors agree that even modest weight loss can have an impact on fertility.
“If they lose a little bit, 7-10% of their body weight, their cycles may return to regular intervals. But, this is not going to occur for everyone,” Snook said.
Does a man's weight impact his fertility?
When doctors address fertility, women often receive much of the counseling, but experts know that male infertility accounts for about one-third of the cases of infertility. And a father’s weight plays into that.
“If a woman is overweight or obese her chances for conception are down ... But, it takes two to make a baby,” Rajeshwari Sundaram, a senior investigator at Eunice Kennedy Shriver National Institute of Child Health and Human Development in Bethesda, Maryland, told TODAY. While a women's weight plays a role in infertility, obese or overweight fathers also contribute to the issue.
“If both parents are obese then their odds for conception for any given cycle is 55% less than people with a normal BMI,” she explained. “Being a dad starts pre-conception, too.”
Weight and IVF
The results on weight loss and IVF are mixed. Many fertility treatment centers refuse to treat people over a certain BMI. That’s often because using anesthesia on people of elevated BMIs comes with problems surgical centers can’t as readily address as hospitals.
“The risk is higher when the weight is higher,” Dokras said. “(Fertility centers) may be restricted with the kind of anesthesia they can administer.”
Losing weight might put women at a healthier weight for anesthesia, but that doesn’t mean she'll get pregnant.
“We haven’t necessarily been able to show that losing weight increases a successful IVF outcome,” Snook said.
But the experts agree that weight is part of addressing fertility struggles.
“It is a holistic approach,” Dokras said. “It is important to communicate what the risks might be for the patient and baby and fertility.”