Introduction The female labor force participation rate is increasing or has remained in high proportion in many countries, and there has been a marked rise in the participation of women with infants in the labor market. In Taiwan, an effort was made to make the workplace friendly for females, especial for mothers-to-be and breastfeeding mothers, under the legal protection. However, some women could not successfully return to work (RTW) after giving birth right after maternity leave.

Objective This study aimed to explore the possible risk factors in the work environment associated with maternal postpartum RTW.

Methods We used the Taiwan Birth Cohort Study, recruiting representative mother-infant pairs using multistage stratified sampling. Participating mothers underwent two home interviews at 6 and 18 months after delivery using structured questionnaires. Mothers actively employed at the beginning of their pregnancy were included. Self-reported 5-point severity gradation of job stress pre- and during pregnancy and time of RTW after childbirth were recorded. Multiple logistic regression analysis was performed to calculate adjusted odds ratios (aOR) and 95% confidence intervals (CI).

Results 9,369 women returning to the same job within 1 year after delivery were included. Among them, 8,478 (90.5%) mothers returned to work after no more than 2 months, when they would be assumed to have a full-paid maternity leave. Compared with those having stationary workload, those suffering from increased job stress during pregnancy had a 1.72 times greater risk of later RTW - between 6 and 12 months, after adjusting for potential confounders. Moreover, among those not returning to work more than 2 months after delivery, the aOR of later RTW was 2.0 (95% CI: 1.25, 3.19) among those with increased job stress.

Conclusions In this prospective birth cohort study, mothers’ prenatal work conditions were significantly related to later RTW for those returning to work within 1 year after childbirth.