RESUMEN
In July 2020, Hong Kong extended statutory paid maternity leave from ten weeks to fourteen weeks to align with International Labour Organization standards. We used the policy enactment as an observational natural experiment to assess the mental health implications of this policy change on probable postnatal depression (Edinburgh Postnatal Depression Scores of 10 or higher) and postpartum emotional well-being. Using an opportunistic observational study design, we recruited 1,414 survey respondents with births before (August 1-December 10, 2020) and after (December 11, 2020-July 18, 2022) policy implementation. Participants had a mean age of thirty-two, were majority primiparous, and were mostly working in skilled occupations. Our results show that the policy was associated with a 22 percent decrease in mothers experiencing postnatal depressive symptoms and a 33 percent decrease in postpartum emotional well-being interference. Even this modest change in policy, an additional four weeks of paid leave, was associated with significant mental health benefits. Policy makers should consider extending paid maternity leave to international norms to improve mental health among working mothers and to support workforce retention.