To evaluate the association between working conditions and adverse pregnancy outcomes by performing a meta-analysis of published studies.
We searched the English-language literature in MEDLINE through August 1999 using the terms standing, posture, work, workload, working conditions, shift, occupational exposure, occupational diseases, lifting, pregnancy complications, pregnancy, small for gestational age (SGA), fetal growth retardation (FGR), preterm, and labor.
We included observational studies evaluating the effect of one or more of the following work-related exposures on adverse pregnancy outcome: physically demanding work, prolonged standing, long work hours, shift work, and cumulative work fatigue score. Outcomes of interest were preterm birth, hypertension or preeclampsia, and SGA.
We conducted a meta-analysis based on 160,988 women in 29 studies to evaluate the association of physically demanding work, prolonged standing, long working hours, shift work, and cumulative work fatigue score with preterm birth. Also analyzed were the associations of physically demanding work with hypertension or preeclampsia and SGA infants. The data were analyzed using the Peto-modified Mantel-Haenszel method to estimate the pooled odds ratios (ORs) and 95% confidence intervals (CIs).
Physically demanding work was significantly associated with preterm birth (OR 1.22, 95% CI 1.16, 1.29), SGA (OR 1.37, 95% CI 1.30, 1.44), and hypertension or preeclampsia (OR 1.60, 95% CI 1.30, 1.96). Other occupational exposures significantly associated with preterm birth included prolonged standing (OR 1.26, 95% CI 1.13, 1.40), shift and night work (OR 1.24, 95% CI 1.06, 1.46), and high cumulative work fatigue score (OR 1.63, 95% CI 1.33, 1.98). We found no significant association between long work hours and preterm birth (OR 1.03, 95% CI 0.92, 1.16).
Physically demanding work may significantly increase a woman's risk of adverse pregnancy outcome.
A meta-analysis of 29 published studies indicates that physically demanding work is significantly associated with preterm birth, hypertension or preeclampsia, and small for gestational age birth weights.
Health Sciences Research, Divisions of Maternal-Fetal Medicine and Department of Obstetrics and Gynecology, University of Michigan Medical School, Ann Arbor, Michigan; and the Departments of Medical Education and Health Services, University of Washington Medical School, Seattle, Washington.
Address reprint requests to: Ellen L. Mozurkewich, MD, Department of Obstetrics and Gynecology, 1500 East Medical Drive, Mott Hospital F4385, Box 0264, Ann Arbor, MI 48109-0264, E-mail: email@example.com
Received April 1, 1999. Received in revised form September 15, 1999. Accepted September 23, 1999.