Effects of neighbourhood socioeconomic disparity on preterm birth during the pandemic: secondary analysis of pregnancy during the pandemic cohort

Preterm birth (PTB) is a major public health concern with significant socioeconomic disparities. While stress-response pathways link neighborhood socioeconomic status (nSES) to PTB risk, overall PTB rates unexpectedly remained stable or declined during the COVID-19 pandemic. Given preliminary evidence suggesting divergent trajectories in pandemic hardship based on neighborhood affluence, it was hypothesized that these counterintuitive trends might reflect a failure to account for how nSES differentially exposed pregnant individuals to pandemic-specific hardships. This study evaluated whether objective pandemic hardship and psychological distress mediated the relationship between nSES and PTB. This study utilized secondary data from N = 5270 pregnancy individuals enrolled in the prospective, longitudinal Pregnancy during the Pandemic cohort across Canada. We tested two serial mediation path models with a measure of baseline objective pandemic hardship and psychological distress included as mediators between nSES and PTB. nSES was geocoded by matching participants’ postal codes to 2021 Canadian Census data using the Vancouver Area Deprivation Index. Exposure to pandemic-specific stressors was assessed at baseline using the Pandemic-Objective Hardship Index (POHI), while psychological distress was assessed using the Edinburgh Postnatal Depression Scale and Patient-Reported Outcomes Measurement Information System Anxiety Scale. PTB was determined via maternal self-reported gestational age at delivery (gestation < 37 weeks). The models were then adjusted for individual SES to capture the unique effects of nSES. The unstandardized indirect pathway from nSES to pandemic objective hardship, psychological distress, then PTB, was significant for both the depression ((B=0.006, p<.001) and the anxiety ((B=0.007, p<.001) models. The significance diminished when adjusted for individual SES. This study is the first to test a comprehensive model of the role of nSES on PTB with an explicit measure of pandemic objective hardship and psychological distress included as mediators. The significance of the indirect serial mediation pathway supports the proposed stress-response mechanism through which global stressors, such as the pandemic, may differentially impact birth outcomes based on socioeconomic disparities across communities. At the same time, the attenuation of the indirect effect by individual SES suggests pandemic-related disparities may be primarily driven by personal socioeconomic resources. The importance of assessing for psychological distress both for risk estimation and as a point of intervention are also discussed.