Effect of maternal work activity on preterm birth and low birth weight.

The association of the prolonged standing required by certain jobs with the rate of preterm births and low birth weight deliveries was examined in New Haven, Connecticut, between 1980 and 1982. In a sample of 1,206 women, the rate of preterm births (births occurring less than 37 weeks from the last menstrual period) was higher among women with jobs requiring prolonged standing (7.7%) compared with those with sedentary (4.2%) or active jobs (2.8%). The odds of preterm delivery in the standing group was 2.72 (95% confidence interval of 1.24-5.95). A significant association between standing on the job and preterm birth was demonstrated when adjustment was made for the following variables in a logistic regression model: parity, smoking, education, caffeine use, marijuana use, race, gestational age at interview, and marital status. The low birth weight (less than 2,500 g) rate was higher among those in the standing group (5.5%) compared with those in the sedentary (4.0%) and active groups (4.0%), but this association was not significant when confounding factors were controlled.