The research does not suggest packing on pounds to get pregnant, or backing off physical activity completely, he said.
"Exercise is a good thing. It's linked to less cardiovascular disease, less cancers, less diabetes," said Mastrogiannis, noting that physical activity is also linked to better pregnancies, easier labors, less pain and fewer induced births.
The bottom line of the study is that normal, non-obese women who want to become pregnant should stick to moderate aerobic exercise, Mastrogiannis said.
"We recommend our patients get moderate aerobic exercise, akin to 30 minutes a day is usually what we say. Walking is very important," he said.
"If they engage in very vigorous exercise -- running, fast cycling, gymnastics or swimming -- more than five hours a week, it makes them less fertile," Mastrogiannis said.
For more on pre-conception health, visit the American Pregnancy Association.
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