EXERCISE DURING PREGNANCY AND PREGNANCY OUTCOME

To investigate the effects of participation in aerobic exercise on pre gnancy outcome, 388 women (mean age = 31.7, range = 18-42) were follow ed from a mean 16.5-wk gestation through delivery. Frequency, duration , and mode of aerobic exercise prior to conception and during the firs t trimester were determined by in-person interviews. Activity patterns during the second and third trimesters were assessed by telephone int erviews. For each lime period, women were categorized into one of the following exercise groups: Level I = aerobic exercise, excluding vigor ous walking, at least three times a week for at least 20 min a time; L evel II = aerobic exercise at least three times a week and 20 min at a time, if and only if vigorous walking is included; Level III = aerobi c exercise less than three times a week, 20 min a time; and Level IV = aerobic exercise less than once a week. Mean birthweight was statisti cally unrelated to level of exercise preconceptionally or in any trime ster. Gestational age, weight gain, and other pregnancy outcomes were also unassociated with exercise level. However, pregnancy symptoms wer e inversely associated with level of exercise; women who exercised mor e earlier in pregnancy reported fewer discomforts later in pregnancy ( P = 0.01). These data suggest that participation in aerobic exercise d uring pregnancy at a level great enough to produce or maintain a train ing effect does not adversely affect birthweight or other maternal and infant outcomes but may be associated temporally with fewer perceived pregnancy-associated discomforts.