Long Working Hours and Shift Work During Pregnancy: Obstetric and Perinatal Outcomes
Summary
This nationwide prospective study followed nearly 100,000 pregnant women in Japan to examine how working hours and night-shift schedules affected pregnancy outcomes. Compared with nonworking women, those who worked during pregnancy had higher risks of threatened miscarriage and threatened preterm labor. Among women working 36+ hours per week with night shifts, the risk of hypertensive disorders of pregnancy was doubled. Long hours (≥36 per week) were also linked to more vacuum/forceps deliveries, and very long weeks (≥46 hours with night shifts) increased the risk of small-for-gestational-age (SGA) infants. In contrast, women working without night shifts had slightly lower odds of gestational diabetes and meconium-stained amniotic fluid.
Why It Matters For Night Shift Workers and Night Owls
For pregnant workers, this study shows that both total weekly hours and night-shift exposure can influence maternal and newborn health. Risks were highest with long schedules that included night shifts, especially in relation to blood pressure disorders, preterm labor warnings, and smaller birth weight. These findings underline the importance of reviewing work patterns during pregnancy. For employers, offering lighter schedules or reducing night work could help protect health outcomes. For workers, it highlights the value of discussing workload and shift timing with supervisors and healthcare providers early in pregnancy.
Notes
Open access.