Researchers grouped seventy women according to whether they exercised regularly, did postpartum exercises only, or never exercised, and measured the strength of their pelvic floors one year after childbirth.
Regular exercisers fared the best, postpartum exercisers fell in between, and non-exercisers had the weakest pelvic floors. Exercise regimens included fitness classes, walking, jogging, running, dancing, swimming, and yoga.
Gordon H and Logue M;Perineal muscle function after childbirth.
Lancet 1985; 2:123-125
Researchers evaluated perineal and pelvic floor outcomes in 460 first-time mothers according to how much they exercised. Women engaging in weight-bearing exercise more than three time weekly were equally likely to have an episiotomy, but only 16 percent experienced anal injury, compared with more than one-quarter of those exercising less often.
Klein MC, et al.; Determinants of vaginal-perineal and pelvic floor functioning in childbirth. American Journal of Obstetrics & Gynecology 1997; 176(2):403-410