The Impact of Occupational Activities During Pregnancy on Pregnancy Outcomes: A Systematic Review and Metaanalysis

Backgroud An increasing number of studies suggest that exposure to physically demanding work during pregnancy could be associated with increased risks of adverse pregnancy outcomes, but the results remain conflicted and inconclusive. Objective To examine the influence of occupational activities during pregnancy on maternal and fetal health outcomes. Data sources Five electronic databases and three gray literature sources were searched up to March 15, 2019. Methods Of Study Selection Studies of all designs (except case studies and reviews) were included, which contained information on the relevant population (women who engaged in paid work during pregnancy), occupational exposures (heavy lifting, prolonged standing, prolonged walking, prolonged bending, and heavy physical workload), comparator (no exposure to the listed physical work demands), and outcomes (preterm birth, low birth weight, small for gestational age, miscarriage, gestational hypertension, pre-eclampsia, gestational diabetes mellitus, stillbirth, and intrauterine growth restriction). Tabulation, Integration, And Results Eighty observational studies (N=853,149) were included. ‘Low’ to ‘very low’ certainty evidence revealed that lifting objects ≥ 11 kilograms (kg) was associated with an increased odds ratio (OR) of miscarriage (OR: 1.31, 95% CI: 1.08 to 1.58, I2=79%), and pre-eclampsia (OR: 1.35, 95% CI: 1.07 to 1.71, I2=0%). Lifting objects for a combined weight of > 100kg per day was associated with an increased odds of preterm delivery (OR: 1.31, 95% CI: 1.11 to 1.56, I2=0%) and having a low-birth-weight neonate (OR: 2.08, 95% CI: 1.06 to 4.11, I2=73%). Prolonged standing was associated with increased odds of preterm delivery (OR: 1.11, 95% CI: 1.02 to 1.22, I2=30%), and having a small-for-gestational-age neonate (OR: 1.17, 95% CI: 1.01 to 1.35, I2=41%. A heavy physical workload was associated with increased odds of preterm delivery (OR: 1.23, 95% CI: 1.07 to 1.41, I2=32%), and having a low-birth-weight neonate (OR: 1.79, 95% CI: 1.11 to 2.87, I2=87%). All other associations were not statistically significant. Dose-response analysis showed women standing more than 2.5 hours per day (versus no standing) had a 10% increase in the odds of having a preterm delivery. Conclusion Physically demanding work during pregnancy is associated with an increased risk of adverse pregnancy outcomes.