A South Korean study of about 1.8 million women examined the association between pregnancy loss and employment type, finding the risk of abortive outcomes and stillbirths were higher among unemployed women, while the risk of having no live birth was higher among employed women.
Women in the social worker industry had the highest risk of no live births. Additionally, manufacturing jobs and health/social work were associated with an increased risk of early abortive outcomes compared with finance/insurance jobs. Consistently higher risks of no live birth were found in manufacturing, wholesale/retail trade, education health/social work, and public/social/personnel service occupations.
“The good news is that the Ministry of Employment and Labor of South Korea is now revising the Industrial Accident Compensation Insurance Act to cover all the abortive outcomes in pregnant women workers,” corresponding author Jung-won Yoon, MD, National Medical Center in Seoul, said in a statement. “Our study contributed to the amendment of this Act, as we presented the impact of the occupational environment on adverse pregnancy outcomes.”
This retrospective cohort study was published in the Journal of Occupational Health.
Data were obtained from the National Health Information Service (NHIS) of South Korea, which encompasses about 97% of the Korean population as a universal health insurance system. The study included information from about 1.8 million pregnant women aged 20 to 49 years from 2010-2019. About 1.2 million of these women were employed, and the remaining 600,000 were unemployed.
The researchers calculated the risk for 3 pregnancy loss outcomes: early abortion (miscarriage, ectopic pregnancy, and molar pregnancy), stillbirth, and no live birth (pregnancy with no record of live birth thereafter, which includes early abortive outcomes and stillbirth).
Employed pregnant women were more likely to be younger, lower income, and have a normal body mass index (BMI) compared with unemployed pregnant women. Additionally, unemployment was associated with a higher prevalence of anemia and history of smoking compared with employment.
Overall, 18%, 0.7%, and 39.8% of pregnancies ended with early abortion outcomes, stillbirths, and no live births, respectively, from 2010 to 2019. The risks of abortive outcomes and stillbirths were higher among unemployed women, whereas the risk of no live birth was higher among employed women. Women in the social worker industry had the highest risk of no live birth. Manufacturing jobs (1.030; 95% CI, 1.013-1.047) and health/social work (1.029; 95% CI, 1.012-1.046) were associated with an increased risk of early abortive outcomes compared with finance/insurance jobs. Consistently higher risks of no live birth were found in manufacturing, wholesale/retail trade, education health/social work, and public/social/personnel service occupations.
The authors noted that these associations may be influenced by the working conditions present in many of these job types, such as physical labor in retail work, erratic work schedules for health care workers, or hazardous materials in manufacturing.
The researchers acknowledged that this study had limitations, and that their results should be interpreted with caution. First, misclassification of unemployment type may have led to bias. Second, the diagnostic codes for pregnancy may have been invalid, especially in health and social work, as better access to obstetric care may have affected outcomes by enabling better detection of early pregnancy loss.
Despite these limitations, the researchers believe their study was able to identify several employment types that may confer high risk for pregnancy loss.
“Our findings highlight the urgent need to assess working conditions to prevent adverse pregnancy outcomes in female workers. Further studies using detailed work environment data are necessary to identify the specific causes of adverse pregnancy outcomes related to each occupation,” the authors concluded.
Kim CB, Choe SA, Kim T, et al. Risk of adverse pregnancy outcomes by maternal occupational status: a national population-based study in South Korea. J Occup Health. Published online January 25, 2023. doi:10.1002/1348-9585.12380