If You Want to Have a Baby, Walk -- Don't Run
I like to be right. Who doesn’t? I especially like to be right when I have stuck my neck out to defend my position, been uniformly criticized by smart and well respected scientists and researchers – and then have a study come out which shows I was right all along.
I began doing research on infertility in the late 1980s and focused on the impact of various lifestyle behaviors and emotions on fertility. I founded a mind/body program for infertility in 1987, based upon some preliminary research, which showed that teaching infertile women various stress-reducing strategies resulted in higher pregnancy rates. As part of the program, I made recommendations about lifestyle changes, based upon the available research. One of the recommendations made to my patients was to decrease the frequency and intensity of their exercise regimen. There hadn’t been any research on the impact of exercise on fertility in humans, but there was some animal research that showed that animals of differing species had lower pregnancy rates when they exercised more.
The problem was that no one else seemed to think that exercise was a problem. I would advise my patients to tone down their exercise sessions, but their infertility specialists would tell them to keep it up. Patients would even be encouraged to exercise more to reduce the stress of treatment. Then in 2006, a study came out in the journal Obstetrics and Gynecology. The conclusion of the study was that vigorous exercise was linked with lower pregnancy rates from IVF treatment: “Regular exercise before in vitro fertilization may negatively affect outcomes, especially in women who exercised 4 or more hours per week for 1-9 years and those who participated in cardiovascular exercise.” I was ecstatic, thinking that now we could finally have a consensus in our recommendations for our patients. But not so fast. Most infertility specialists didn’t believe the results, and they criticized the design of the study.
Fast forward to March 16, 2012. The American Society of Reproductive Medicine (ASRM) sent out a bulletin to all 10,000 members, highlighting a new study that indicated that vigorous exercise delayed pregnancy in normal weight women. In this study, Danish researchers followed 3628 women who were planning on becoming pregnant. They completed questionnaires every two months for 12 months or until they achieved pregnancy. For normal weight women, the more vigorous their exercise, the longer it took them to get pregnant. Moderate exercise was associated with the shortest time to conception. There was no relationship for obese women however.