Physical activity and the risk of spontaneous preterm delivery.

An epidemiologic case-control study exploring possible risk factors for preterm delivery was undertaken at Yale-New Haven Hospital during 1977. The study groups consisted of 175 mothers of singleton preterm infants and 313 mothers of singleton term infants. Analysis of questionnaire responses provided no evidence that employment, housework, child care and leisure-time physical activity during pregnancy increased the risk of preterm delivery. Women who participated in sports or physical fitness exercises during pregnancy were found to have a significantly decreased risk of preterm delivery as compared to those who were not similarly active; this finding suggests that certain forms of moderate physical activity may actually protect against preterm delivery.