Maternal Instinct

In July 2020, Hong Kong extended statutory paid maternity leave from 10 to 14 weeks to align with International Labour Organization standards. Not only was this a great day for new mums, but it also provided a rare opportunity to study directly and immediately the implications of such a change on the mothers concerned, with a particular focus on postnatal depression, if any.

The research team which undertook the research comprised experts from HKUMed’s School of Public Health and School of Nursing, as well as collaborators from Singapore’s Duke-NUS Medical School and Canada’s University of British Columbia. Their study revealed a 22 per cent decrease in postnatal depressive symptoms among mothers and a 33 per cent reduction in mothers reporting that baby care interfered with their emotional well-being.

Significant benefits

Professor Quan Jianchao, Clinical Assistant Professor in the School of Public Health, and senior author of the study, said: “Even this modest change in policy, an additional four weeks of paid leave, was associated with significant mental health benefits. Policymakers should consider extending paid maternity leave to international norms to improve mental health among working mothers and to support workforce retention.”

For the study, the team used the policy enactment as an observational natural experiment to assess the mental health implications of this policy change on probable postnatal depression – that is, Edinburgh Postnatal Depression Scale (EPDS) scores of 10 or higher – and postpartum emotional well-being.

“The EPDS is widely clinically used and has been validated in Hong Kong,” explained Professor Quan. “The reason we use the term ‘potential’ in our findings is that this is a screening tool. Postnatal depression (or indeed depression) is a clinical diagnosis – it can only be diagnosed by a physician, as opposed to diabetes or hypertension that is diagnosed by a laboratory test or measurement.”

Using an opportunistic observational study design, the team recruited 1,414 survey respondents who had given birth either before the policy implementation during August to December 2020, or after the implementation, between December 2020 and July 2022. Participants had an average age of 32, for most this was their first child, and the majority had skilled occupations.

“Our results show that the policy was associated with a 22 per cent decrease in mothers experiencing postnatal depressive symptoms and a 33 per cent decrease in postpartum emotional well-being interference,” said Professor Quan. “This was somewhat surprising given the modest length of leave extension, though it is hard to attribute the causality definitely in these natural experiments.”

The study comes at a time of demographic challenges in East Asia when birth rates are falling, the proportion of elderly in populations is growing and many governments are seeking ways to encourage young people to have children.

In Hong Kong, only 52 per cent of women currently participate in the workforce, compared to 64 per cent of men, so retaining female employees is important to address the labour shortage. Women of child-bearing age (25–34 years old) have the highest workforce participation rate (80 per cent), making them the most likely to benefit from an optimal maternity leave policy.

Postnatal depression is a serious mental disorder which can affect mothers up to a year after childbirth. About 30 per cent of new mothers in Hong Kong experience postnatal depression, which is markedly higher than the global average of 18 per cent. The figure for Mainland China is 14 per cent and just 3 per cent in Singapore. Maternity leave policy could have important implications for public health, including improved maternal mental and physical health and higher breastfeeding rates.

18 weeks leave

“The International Labour Organization, which is part of the United Nations, actually mandates a minimum maternity leave period of 14 weeks and recommends increasing it to at least 18 weeks to ensure an adequate rest and recovery time for the mother,” said Professor Quan. “In 2021, 52 countries met or exceeded this 18-week standard. The US is a notable exception/ outlier with no nationally mandated paid leave.

“Longer periods and more flexible arrangements such as shared parental leave (rather than separate maternity/ paternity) can also be considered. Many countries offer shared parental leave – Singapore announced on their National Day in August 2024 an additional 10 weeks of government-paid shared leave to bring it up to 30 weeks by 2026. Flexibility should be beneficial as people tend to make the best decisions for their circumstances but notably, men have higher labour force participation and higher wages so the costs may be higher.”

Professor Quan pointed out that the Hong Kong Government has launched other family-friendly initiatives too, for example, a Newborn Baby Bonus.

The research findings were published in the healthcare journal Health Affairs.