LAUSR

Background Negative effects of manual handling of burdens on pregnancy outcomes are not elucidated in Finland. This study examines the association between perinatal outcomes and occupational exposure to manual handling of burdens. Methods The study cohort was identified from the Finnish Medical Birth Register (MBR, 1997-2014) and information on exposure from the Finnish job-exposure matrix (FINJEM) 1997-2009. The cohort included all singleton births of mothers who were classified as 'service and care workers' representing the exposure group (n=74 286) and 'clerks' as the reference (n=13 873). Study outcomes were preterm birth (PTB) (<37 weeks), low birthweight (LBW) (<2500 g), small for gestational age (<2.5th percentile), perinatal death (stillbirth or early neonatal death within first seven days) and eclampsia. We used logistic regression analysis to calculate odds ratio (OR) and adjusted for maternal age, marital status, BMI, parity and smoking during pregnancy. Results The risks of PTB [OR 1.16, 95% confidence interval (CI) 1.06-1.27], LBW (OR 1.12, 95% CI 1.01-1.25) and perinatal death (OR 1.51, 95% CI 1.09-2.09) were significantly higher among the high exposure group than in the reference group. All adverse outcomes were statistically insignificant among primiparous women except perinatal death (OR=1.95, 95% CI 1.13-3.39). Conclusions The study indicates that the risk of adverse pregnancy outcomes might be more common among women that are highly exposed to occupational manual handling of burdens. The results should be interpreted with caution due to the use of occupational level exposure. Further studies with information on individual level exposure and start of maternity leave are recommended.