Occupational exposures and sick leave during pregnancy: results from a Danish cohort study

Objective This study aimed to investigate associations between work postures, lifting at work, shift work, work hours, and job strain and the risk of sick leave during pregnancy from 10–29 completed pregnancy weeks in a large cohort of Danish pregnant women. Methods Data from 51 874 pregnancies in the Danish National Birth Cohort collected between 1996–2002 were linked to the Danish Register for Evaluation of Marginalization. Exposure information was based on telephone interviews. Hazard ratios (HR) with 95% confidence intervals (95% CI) were calculated by Cox regression analysis, using time of first episode of sick leave as the primary outcome. Results We found statistically significant associations between all the predictors and risk of sick leave; for non-sitting work postures (HR range 1.55–2.79), cumulative lifting HR trend 1.29, 95% CI 1.26–1.31, shift work (HR evening 1.90, 95% CI 1.73–2.09, HR night 1.52, 95% CI 1.15–2.01), monthly night shifts HR trend 1.12, 95% CI 1.11–1.14, increasing weekly work hours HR trend 0.93, 95% CI 0.91–0.95 and high job strain HR 1.52, 95% CI 1.42–1.63. Some exposures influenced HR in either a positive or negative time-dependent way. Conclusion Our results support previous findings and suggest that initiatives to prevent sick leave during pregnancy could be based on work conditions. Preventive measures may have important implications for pregnant women and workplaces.