By: Kristina Grish
You eat right and workout regularly, so conceiving should be a cinch, right? Not quite. Recent research shows that though your gym routine may improve your health, reduce stress, and keep your weight in check, working out too much can result in lower fertility. So how do you know the difference between a healthy workout and going overboard? We went straight to the experts to find out.
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The Guideline Gap
"We've known that weight is an important factor in fertility, but considering the role of exercise is a recent phenomenon in Western medicine," explains Robert Brzyski, MD, PhD, professor of obstetrics and gynecology at the University of Texas Health Science Center at San Antonio and chair of the ethics committee of the American Society of Reproductive Medicine (ASRM). Preliminary research suggests that regular workouts may actually improve reproductive function: A study in Obstetrics & Gynecology concluded that women who exercised 30 minutes or more daily had a reduced risk of infertility due to ovulation disorders. On the other hand, some data links too much vigorous exercise with lowered fertility, as both a 2009 study in Human Reproduction and a Harvard study of elite athletes found. Clearly fitness activity plays a role in a woman's chances of conceiving, yet "studies on which to base fitness advice are still difficult to find and often contradictory, so it's been hard to give women definitive guidelines to follow," Dr. Brzyski says.
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The Ideal Weight to Conceive
The numbers on your scale can be key to your ability to conceive. Exercise, of course, can help regulate your weight, but only if you've got a realistic grip on the numbers. According to a 2010 University of Texas Medical Branch at Galveston study, nearly 48 percent of underweight, 23 percent of overweight, and 16 percent of normal-weight reproductive-age women don't accurately assess their own body weights. Such a misperception could have an impact on your health habits, which could then affect your fertility.
Moreover, your ideal weight for hitting 5K PRs or fitting into your skinny jeans may not be the weight most conducive to conceiving. "You don't have to be a size 6 to have a baby," says lead study researcher and ob-gyn Abbey Berenson, MD. "This isn't about what looks good on a runway. It's about making your body healthy enough to carry a child." The sweet spot for many women translates to the normal BMI range (18.5 to 24.9), which is associated with optimal reproductive function. Research shows that 12 percent of infertility cases may result from being under that range and 25 percent from being over it. The two extremes tax the body in ways that disturb hormone production and ovulation, Dr. Brzyski says.How to Boost Your Fertility
The default stance -- mostly because there have been no controlled studies of exercise in women who are trying to get pregnant naturally -- is that normal-weight women should work out at the "public health" dosage of 150 minutes weekly, says Sheila Dugan, MD, chair of the American College of Sports Medicine's Strategic Health Initiative on Women, Sport, and Physical Activity. That translates to 30 minutes of moderate-intensity activity (you break a sweat and are winded but can still speak in short phrases) five days a week. Under- or overweight women should seek evaluation from a certified fitness professional, like an exercise physiologist or trainer, to tailor a program based on their energy input and output, Dr. Dugan says.
Some specialists are going beyond this generic mandate. Here's what several top docs recommend for their patients and FITNESS readers.
- If you're a normal weight: There is no need to give up your regular runs or, say, Zumba classes. Just keep your workouts to an hour or less a day. If your cycle is irregular or you haven't conceived after a few months, cut back further on exercise. Also, this isn't the time to train for your first competitive event or start a rigorous gym class. "If you make a dramatic increase in your exercise level, even if BMI or body fat percentage stays the same, the stress can have a negative effect on reproductive hormone production and fertility," Dr. Brzyski says.
- If you're underweight: Aim for 2,400 to 3,500 calories a day to gain the weight that will get you into the normal BMI range, or body fat above 12 percent. If you're exercising five or more days a week, consider cutting back to three. Alice Domar, PhD, executive director at the Domar Center for Mind/Body Health at Boston IVF, says hatha yoga appeals to many women in this category: "It keeps them fit and toned without the potential adverse impact of vigorous exercise."
- If you're overweight: Trim calories and gradually up your exercise to reach a fertility-friendly BMI. Aim for 60 minutes of cardio five days a week, and strength-train for 30 minutes three times a week. Even so, "you can work out too hard even if you're overweight," says Sami David, MD, a reproductive endocrinologist in New York City and coauthor of Making Babies: A Proven 3-Month Program for Maximum Fertility. "Build up your tolerance slowly."
- If you're undergoing fertility treatments: Talk to your doctor before you step on that treadmill. Intense, vigorous or high-impact exercise may cause ovaries that have been enlarged by the use of fertility drugs to twist -- a medical emergency.
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