BACKGROUND: Although maternal employment is considered a risk factor
for low birthweight (LBW), the manner in which employment might affect
birthweight is poorly understood. In this analysis, selected characteristics of
employment during pregnancy were examined for effects on pregnancy outcomes.
METHODS: Work characteristics included the number of hours per week, physical
activities, and environmental conditions. The outcomes of interest were fetal
growth retardation (less than 2500 grams at term) and preterm delivery (less
than 37 weeks). The study population consisted of 2711 non-Black, married
mothers who participated in the 1980 National Natality Survey (NNS). The NNS
data were merged with data from the 1977 revision of The Dictionary of
Occupational Titles (DOT) from which measures of occupational physical
activities and environmental exposures were obtained. Logistic regression was
used in the analysis.
RESULTS: Those who worked 40 or more hours per week were
more likely than women who worked fewer hours to have a low birthweight
delivery at greater than or equal to 37 weeks. No physical or environmental
characterics of work were associated with low birthweight or preterm delivery.
CONCLUSIONS: Non-Black married American women may face a risk of delivering
low-birthweight babies at or near term only if they work 40 or more hours each
week. However, the lack of risk associated with other characteristics of work
may be a function of measurement error in the DOT data source or of low levels
of exposure in the analysis population.