A prospective cohort study of air pollution and postpartum depression

Dr. Wesselink’s study will leverage data from Pregnancy Study Online (PRESTO), an ongoing web-based preconception cohort study, to examine the effect of prenatal air pollution exposure on risk of postpartum depression.

Postpartum depression is a common complication of pregnancy, is a major contributor to pregnancy-related morbidity and mortality, and has adverse consequences for both the birthing person and their infant. There are also stark racial disparities in postpartum depression symptomatology and treatment, with Black and Hispanic birthing people exhibiting more severe symptoms relative to white birthing people; these groups are also less likely to receive and continue optimal postpartum mental health treatment. Despite the tremendous population-level burden of postpartum depression, particularly among minoritized groups, few risk factors have been identified, thus precluding opportunities for prevention. Identification of modifiable risk factors for postpartum depression is important for advancing reproductive health equity and promoting reproductive justice. 

Air pollution has been associated with adverse mental health outcomes and neuropathology in the general population, but its association with postpartum depression is less well studied. There are also significant limitations in the existing literature, including 1) under-ascertainment of postpartum depression, 2) lack of consideration of particulate matter components, 3) limited assessment of critical windows of exposure, and 4) no evaluation of the interaction between air pollution and ambient heat in shaping postpartum depression risk. In the proposed project, we will leverage data from Pregnancy Study Online (PRESTO), an ongoing web-based preconception cohort study, to examine the effect of prenatal air pollution exposure on risk of postpartum depression. Specific aims are as follows:  

•    Aim 1: Measure the effect of prenatal trimester-specific ambient air pollution concentrations (NO2, O3, PM2.5, and PM2.5 components) on postpartum depression risk and identify critical windows of exposure using distributed lag non-linear models
•    Aim 2: Assess the effect of prenatal trimester-specific outdoor heat on risk of postpartum depression and use distributed lag non-linear models to identify critical windows of exposure
•    Aim 3: Apply mixtures modeling to measure the independent and joint effects of air pollution and heat exposures on risk of postpartum depression and conduct an exploratory analysis incorporating exposures related to neighborhood disadvantage and green space into the mixture

The successful completion of these aims will inform development of interventions and policies aimed at reducing pregnant people’s exposure to air pollution, particularly in the context of ongoing climate change. We aim to transform clinical practice, to both identify pregnant people at higher risk of postpartum depression and work with pregnant people to reduce their exposures during critical windows. These aims are directly responsive to the Health Effects Institute’s Strategic Plan, which emphasizes the need to consider complex questions for the air pollution mixture, including multiple air pollutants and other relevant stressors (e.g., climate change, neighborhood disadvantage) and identification of sensitive or at-risk populations.