"While it may seem counterintuitive, women who regularly exercised for four or more hours per week in the previous nine years or less were 40% less likely to have a live birth after their first cycle of in vitro fertilization (IVF) than women who didn't exercise, according to a new study published in the October issue of Obstetrics & Gynecology. Regular exercisers were also twice as likely to have an implantation failure or pregnancy loss after undergoing IVF than women who did not exercise. Cardiovascular exercise, in particular, was associated with a 30% lower likelihood of successful live birth compared with nonexercisers.
...With a grant from the National Institutes of Health, researchers analyzed prospective data on 2,232 women who underwent IVF treatments at one of three clinics in the Boston area from 1994 to 2003. Of these women, 61.3% reported that they exercised regularly, and 38.5% reported that they didn't exercise. Women exercisers were broken down into three different groups based on their primary type of exercise: walking, cardiovascular (eg, jogging, aerobics, treadmill), and other (eg, swimming, yoga, team sports). These three groups were further broken down into four basic categories based on the number of hours per week and the number of years that they had been exercising.
The study found that, in general, women who reported walking for exercise had essentially the same likelihood of successful live births after their first IVF treatment when compared to nonexercisers. However, the subgroup of women who walked for four or more hours per week for the previous nine years or less were 50% less likely to have a successful live birth after IVF compared with nonexercisers.
The good Chinese medicine docs all say that at the very least, menstruation is a time to rest, and don't even do much yoga (especially inversion poses) that will interfere with the downward flow.
But pregnancy is even more of a time when you need rest, and less stress. When I had my first miscarriage, at 12 weeks, I was a stress bucket and was jogging all the time. And what did I do the day before I actually miscarried? Went on a bike ride. Heavy cardiovascular exercise IS a stress on your body. I also think in general I don't need to be such a crazy goal-oriented exerciser. That in itself is stressful. Geez.