The relationship between occupational classification and low birth weight in a national sample of white married mothers.

The relationship between occupational classification and Low Birth Weight singletons (LBW; less than 2500 g) was studied in a sample of white married mothers employed in the National Natality Survey 1980 (N = 3300). Univariate analyses included relationship between birth weight and occupation, smoking, alcohol, parity, age, education, prenatal care, weight gain during pregnancy, gestation and sex of the singleton. Occupation was significantly associated with LBW (P less than 0.05). The LBW rate was higher among blue collar workers (162 per 1000) compared to white collar workers (132 per 1000). The mean birth weight of singletons among blue collar workers was also significantly lower compared to those among white collar workers (P less than 0.057). However, after adjusting simultaneously for the effect of the confounding variables in multiple regression analysis, occupation was no longer a significant predictor of LBW. The extent to which the validity problems may limit the interpretation of the study are discussed.