How maternity leave affects maternal and infant physical health?

Results

Figure 3. Logic model of the possible causal relationship between exposure to lack of (paid) maternity leave and health outcomes: breastfeeding outcomes, maternal and infant physical health

Fig. 3 presents the logic model for this investigation, demonstrating the casual relationship between exposure to maternity leave and leave without pay and breastfeeding outcomes as well as infant and maternal physical health indicators. This logic model, inferred from literature review, was designed with a process-focused approach and attempts to illustrate the complex causal pathways linking risk factors to outcomes. Multiple variables may mediate the effect of maternity leave on health outcomes through 2 pathways. The first pathway focuses on potentially health-detrimental behaviors such as unhealthy diet, lack of nutrition and exercise, birth delivery mode and fatigue. The second pathway emphasizes on the significance of stress physiologically, affecting both the nervous and immune system activity of the mother. These mediators are all established risk factors affecting maternal and or infant health [1] [2]. Effect modifiers in this model include socioeconomic status (SES), marriage status, single child status, occupation, county, father involvement, length of maternity leave, and social support. These result in different accesses to additional resources and support systems, which may mitigate health effects or conversely, intensify stress and health risks associated with inadequate leave. Confounders include age, income, education, and financial situation (all aspects of SES). These factors independently influence both leave accessibility and health outcomes directly. A higher SES may lead to better health outcomes regardless of maternity leave, creating a potential confounding effect in the analysis.

The cut-off point for maternity leave was determined to be 12 weeks and yes/no for breastfeeding outcomes. The forest plot in Fig. 4 reveals that all the individual studies' odds ratios (ORs) are less than 1, suggesting that shorter maternity leave (<12 weeks) is associated with lower odds of breastfeeding. In addition, both the fixed and random-effects models show a combined odds ratio less than 1, indicating a consistent finding across studies that shorter maternity leave is associated with lower breastfeeding rates. The random-effects model also has a wider confidence interval (CI) than the fixed-effect model, reflecting the high heterogeneity (I² = 85%) among the studies. The CIs for both the fixed-effect and random-effect models do not cross 1, suggesting that the association is statistically significant. Hence Fig. 4 demonstrates that across multiple studies, shorter maternity leave is consistently associated with lower odds of breastfeeding. The high heterogeneity (I² = 85%) suggests variability among studies, making the random-effects model more appropriate for interpreting the combined effect. Both models suggest a significant association, with the random-effects model accounting for between-study differences.

​*While 3 of the 5 studies all display Mirkvoic to be the first author, note that these studies all investigated different exposures, outcomes and data samples.

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The correlation between maternal physical health and maternity leave length or pay varies significantly in the studies review in this investigation. Five of the seven studies suggest a marginal positive correlation. The Grice study [3] suggests that high levels of work-to-interpersonal family conflict is weakly negatively associated with maternal physical health. The Tucker study [4] suggests mothers of high economic hardship generally suffered worse levels of physical health and less stable trajectories. The Hewitt study [5] observed improved maternal health with the introduction of a paid parental leave program of 18 weeks, although minimal. The Dagher study [6], using two statistical methods for analysis, indicates a marginally significant linear positive association between leave duration and physical health. The Chatterji study [7] suggests less than 8 weeks of paid leave is associated with a reduction in overall health status. The Jou study [8], however, reveals a 51% decrease in the odds of re-hospitalization postpartum for mothers with paid leave compared to those of unpaid or no leave. They also had 1.8 times odds of doing well with exercise and stress management. Yet the Ahammer [9] study suggests long-term maternal health is not affected by the extension of leave from 6 to 8 weeks. Hence comprehensively, the studies reviewed demonstrate a generally positive yet minimal relationship between maternal physical health and leave, suggesting an extension in leave duration or pay would likely potentially induce health benefits for mothers.

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Similarly, the association between maternity leave and infant physical health also varies. The Jou study[10] suggests women who took paid maternity leave experienced a 47% decrease in the odds of re-hospitalizing their infants. No significant differences, however, were found between women taking 12 or fewer weeks and women taking no paid maternity leave. Furthermore, though infant overall health status improves when paid leave increases to 7-12 weeks, it decreases back to previous levels when leave is extended beyond 12 weeks. The Ahammer study [11] also finds no evidence for significant effects of leave extension on children’s health at birth or long-term health, including low birth weight. The Sydsjö study confirms that use of social benefits and increased rest during pregnancy did not significantly influence birth weight. Yet the Dinh study [12] suggests the occurrence of infant low birth weight is significantly linked to pre-natal maternity leave duration. The heterogeneity of leave duration association with birthweight between different studies may thus be attributed to the vast distinction in national incomes between the nations of Austria, Sweden and Vietnam, as mentioned particularly in the Dinh study. Comprehensively, it may be concluded there generally exists a weak, if any, association between short-term infant health and maternity leave duration for developed nations while this association may be significant in poorer countries. However, more research is warranted for further confirmation.

The ROBINS-I tool is used to assess the risk of bias of all 14 studies investigated to evaluate the effectiveness of their respective interventions as randomisation could not be used to allocate interventions in the case of maternity leave. Traffic light diagrams are constructed for studies relating to each of the three outcome, evaluating study design, results and presentation, providing an overall judgement of risk of bias (Fig. 5, 6, 7.).​

[1] Andres et al., ‘Maternity Leave Access and Health’.

[2] Whitney et al., ‘Length of Maternity Leave Impact on Mental and Physical Health of Mothers and Infants, a Systematic Review and Meta-Analysis’.

[3] Mira M Grice et al., ‘Giving Birth and Returning to Work: The Impact of Work-Family Conflict on Women’s Health after Childbirth.’, Annals of Epidemiology, 24 August 2007, https://doi.org/10.1016/j.annepidem.2007.05.002.

[4] Jenna N Tucker et al., ‘Return to Work, Economic Hardship, and Women’s Postpartum Health.’, Women & Health, n.d., https://doi.org/10.1080/03630242.2010.522468.

[5] Belinda Hewitt, Lyndall Strazdins, and Bill Martin, ‘The Benefits of Paid Maternity Leave for Mothers’ Post-Partum Health and Wellbeing: Evidence from an Australian Evaluation.’, Social Science & Medicine (1982), 14 April 2017, https://doi.org/10.1016/j.socscimed.2017.04.022.

[6] Rada K Dagher, Patricia M McGovern, and Bryan E Dowd, ‘Maternity Leave Duration and Postpartum Mental and Physical Health: Implications for Leave Policies.’, Journal of Health Politics, Policy and Law, 4 December 2013, https://doi.org/10.1215/03616878-2416247.

[7] Pinka Chatterji and Sara Markowitz, ‘Family Leave after Childbirth and the Mental Health of New Mothers.’, The Journal of Mental Health Policy and Economics, n.d.

[8] Judy Jou et al., ‘Paid Maternity Leave in the United States: Associations with Maternal and Infant Health.’, Maternal and Child Health Journal, n.d., https://doi.org/10.1007/s10995-017-2393-x.

[9] Alexander Ahammer, Martin Halla, and Nicole Schneeweis, ‘The Effect of Prenatal Maternity Leave on Short and Long-Term Child Outcomes.’, Journal of Health Economics, 30 January 2020, https://doi.org/10.1016/j.jhealeco.2019.102250.

[10] Judy Jou et al., ‘Paid Maternity Leave in the United States: Associations with Maternal and Infant Health.’

[11] Alexander Ahammer, Martin Halla, and Nicole Schneeweis, ‘The Effect of Prenatal Maternity Leave on Short and Long-Term Child Outcomes.’

[12] P H Dinh et al., ‘Maternal Factors Influencing the Occurrence of Low Birthweight in Northern Vietnam.’, Annals of Tropical Paediatrics, n.d., https://doi.org/10.1080/02724936.1996.11747845.