The impact of working hours on pregnancy intention in childbearing-age women in Korea, the country with the world’s lowest fertility rate
Level 4 - case-series / case-control
Cross-sectional survey analysis with propensity score matching
OpenAlex W4384820750 · doi:10.1371/journal.pone.0288697
What was done
Analyzed data from 22,731 women aged 15–49 from the Korean National Health and Nutrition Examination Survey (KNHANES). The authors applied propensity score matching on age and birth year between pregnant and non-pregnant women. An XGBoost machine learning model was used to rank factors related to pregnancy intentions, followed by cluster analysis and multivariable logistic regression evaluating pregnancy odds across 5-hour increments of weekly working hours.
What was found
Weekly working hours emerged as the most important feature affecting pregnancy intention in the XGBoost model. Cluster analysis identified the subgroup with the highest pregnancy likelihood worked an average of 34.4 ± 12.9 hours per week. In logistic regression, working 40–45 hours per week (OR 2.009, 95% CI: 1.581–2.547, p < .001) and 35–40 hours per week (OR 1.450, 95% CI: 1.001–2.040, p < .05) were associated with higher odds of pregnancy compared to other working hours.
Why it matters
In South Korea, which faces the lowest fertility rate globally alongside long working hours, identifying an association between standard workweeks (35–45 hours) and pregnancy odds highlights working hours as a potential target for family-planning policies.
Limits
The study is cross-sectional, preventing causal inference and leaving open the possibility of reverse causation (e.g., women planning pregnancy actively reducing or standardizing work hours). The abstract blurs the distinction between actual pregnancy status and pregnancy intention. Unmeasured confounders such as partner work hours, household income, and job security were not described.
Cited by
- supports The birth rate in South Korea is currently 0.7.