Effect of parents' occupational exposures on risk of stillbirth, preterm delivery, and small-for-gestational-age infants

Epidemiologic research on the effects of parental occupational exposures on fetal development has been limited. The National Natality and Fetal Mortality surveys obtained applicable data on probability samples of live births and fetal deaths which occurred in the US in 1980 among married women. Analyses were conducted for case groups of stillbirths (2,096 mothers, 3,170 fathers), preterm deliveries (less than 37 weeks completed gestation) (363 mothers, 552 fathers), and small-for-gestational-age infants (218 mothers, 371 fathers) compared with controls. Occupational exposures were defined by industry of employment and by imputed exposures based on a job-exposure linkage system. For stillbirth, maternal work in the rubber, plastics, and synthetics industry (odds ratio (OR) = 1.8, 95% confidence interval (Cl) 0.8-4.0) and lead exposure (OR = 1.6, 95% Cl 0.8-3.1), and paternal employment in the textile industry (OR = 1.9, 95% Cl 1.2-2.9), had the largest odds ratios. Preterm birth was most strongly associated with maternal lead exposure (OR = 2.3, 95% Cl 0.7-7.0), corroborating previous findings. Twofold increased risk of preterm delivery was found with paternal employment in the glass, clay, and stone; textile; and mining industries. Paternal exposures to x-rays and polyvinyl alcohol were associated with 1.5-fold increase in risk. The occupation of the mother was not associated with delivery of a small-for-gestational-age infant, in contrast to paternal employment in the art (OR = 2.6, 95% Cl 1.2-5.6) and textile industries (OR = 2.5, 95% Cl 1.3-4.7). Several toxic agents were associated with risk elevation of 1.3 or greater for fathers, most notably benzene (OR = 1.5, 95% Cl 1.1-2.3). In spite of limitations in the exposure data, the size of the exposed populations, and possible confounding, the results in this study encourage further evaluation of the effects of maternal exposure to lead and possibly solvents, as well as paternal exposure in the textile industry and to x-rays and benzene.