Postpartum health, extreme heat, and the urban environment

Shreya Patel

doi:10.17918/00011544

Maternal and postpartum morbidity and mortality remain significant public health concerns in Philadelphia, with persistent racial and geographic disparities that disproportionately affect Black birthing people. These disparities may be explained by structural factors, including residential segregation, which has produced differential access to resources and differential exposure to environmental hazards across neighborhoods. The postpartum year remains a vulnerable period for maternal health, as biological recovery from childbirth overlaps with new caregiving responsibilities and psychosocial stressors. This vulnerability may be further exacerbated by climate change, which is increasing in the frequency, duration, and intensity of extreme heat days. Yet, little is known about how extreme heat affects health in the year following childbirth or how neighborhood context modifies these risks. This dissertation examined the intersection of postpartum health, extreme heat, and the urban environment in Philadelphia through three connected aims: (1) characterizing the spatial distribution of pregnancy-associated mortality, (2) examining the association between extreme heat and morbidity in the late postpartum period, and (3) identifying individual- and neighborhood-level factors that modify heat-related health risks during the late postpartum period. Aim 1 characterized the spatial patterning of pregnancy-associated, pregnancy-related, and external-cause mortality across Philadelphia neighborhoods between 2012 and 2021 using Bayesian spatial models. Aim 2 examined the association between extreme heat exposure and emergency department (ED) visits during the late postpartum period (43-365 days after delivery) among Medicaid-enrolled postpartum individuals in Philadelphia during the warmest months (May-September) of 2016-2019 using a time-stratified case-crossover design with distributed lag nonlinear models. Finally, in Aim 3 we identified individual- and neighborhood-level characteristics that modified the association between extreme heat and postpartum ED visits using a case-time series design with distributed lag nonlinear models. In Aim 1, we observed large racial disparities in pregnancy-associated and pregnancy-related mortality, with non-Hispanic Black mothers having rates up to three times greater than non-Hispanic White mothers. Higher rates were concentrated in North and West Philadelphia, areas characterized by structural disadvantage with high racialized economic segregation. In Aim 2, elevated minimum temperatures were significantly associated with increased risk of ED visits, with mental health-related visits showing the strongest and most consistent association with extreme heat. In Aim 3, postpartum people who were non-Hispanic Black, within six months of delivery, younger, or living in more structurally disadvantaged neighborhoods faced the greatest heat-related ED visit risk. Collectively, these findings establish that the postpartum year represents a critical period for maternal health research, clinical care, and climate adaptation efforts. Integrating postpartum health into heat preparedness planning, strengthening postpartum surveillance, and improving the neighborhood conditions that drive unequal exposure and adaptive capacity to extreme heat will be essential to reducing inequities and protecting postpartum health in a changing climate.

Postpartum health, extreme heat, and the urban environment

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Postpartum health, extreme heat, and the urban environment

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