Effect of working hours and shift work on preterm birth among Australian women in paid work during pregnancy: Prospective cohort study

Abstract

Objective

In Australia, the rate of preterm births increased from 8.3 % in 2010 to 8.7 % in 2021, posing risks not only during pregnancy and the neonatal period but also for long-term offspring development. While global studies highlight predictors of preterm birth, limited research explores the link between working conditions, such as long working hours, shift work, and preterm birth in Australian women.

Study design

Prospective cohort study.

Methods

This study analysed data from the Australian Longitudinal Study on Women's Health, including 2241 employed women who reported 2522 singleton births between 1996 and 2018. Mixed-effects logistic regression was used to account for repeated births from the same women. Data analysis was performed using STATA version 17.

Results

Long working hours were initially associated with an increased risk of pre-term birth (AOR 1.61, 95 % CI: 1.02–2.55), but this association became non-significant after adjusting for obstetric and health factors (AOR 1.21, 95 % CI: 0.76–1.92). Similarly, shift work showed no significant association with preterm birth (AOR 0.59, 95 % CI: 0.31–1.13). Low educational status (AOR 1.86, 95 % CI: 1.04–3.31), smoking (AOR 2.48, 95 % CI: 1.17–5.25), gestational hypertension (AOR 2.75, 95 % CI: 1.32–5.23), primiparity (AOR 2.02, 95 % CI: 1.13–3.63), asthma history (AOR 2.01, 95 % CI: 1.05–3.84) and lack of private health insurance (AOR 1.86, 95 % CI: 1.14–3.05) remained significantly associated with higher odds of preterm birth.

Conclusion

This study initially found a link between working over 40 hours per week and preterm birth, but this association was nullified after adjusting for health and obstetric factors. Additionally, shift work showed no significant association with preterm birth. Low educational status, smoking, gestational hypertension, asthma, primiparity, and lack of private health insurance were significantly associated with preterm birth. Addressing chronic diseases and social inequalities is crucial to reducing preterm birth rates.