# Association of early pregnancy warm season exposure and neighborhood heat vulnerability with adverse maternal outcomes: A retrospective cohort study

## TL;DR

Exposure to warm weather during early pregnancy and living in heat-vulnerable neighborhoods increases the risk of complications like preeclampsia and infections in pregnant women.

## Contribution

This study identifies trimester-specific warm season exposure and neighborhood heat vulnerability as independent risk factors for adverse maternal outcomes.

## Key findings

- First trimester warm season exposure increases odds of gestational hypertension, preeclampsia, and genitourinary infection.
- Higher neighborhood heat vulnerability is linked to increased odds of preeclampsia and genitourinary infection.
- Both early pregnancy warm weather exposure and neighborhood vulnerability independently raise risks of maternal complications.

## Abstract

Rising ambient temperatures threaten vulnerable populations such as pregnant women, with urban populations bearing a greater risk due to the urban heat island effect. Here, we assessed the independent effects of trimester-specific warm season exposure during pregnancy and neighborhood heat vulnerability on maternal outcomes, including gestational diabetes, hypertensive disorders of pregnancy, genitourinary infections, and operative delivery.

This retrospective study analyzed 819 participants from the Stress in Pregnancy Study (2009–2014), a longitudinal birth cohort study in New York City. Generalized linear models examined associations between trimester-specific warm season exposure, New York City Heat Vulnerability Index (ranging 1–5), and adverse maternal outcomes, adjusting for demographics, parity, and substance use.

First trimester warm season exposure was associated with increased odds of gestational hypertension (adjusted odds ratio [AOR] 4.50, 95%CI 1.17–17.27), preeclampsia (AOR 4.38, 95%CI 1.51–12.75), and genitourinary infection (AOR 2.27, 95%CI 1.14–4.51). Each unit increase in heat vulnerability index was associated with increased odds of preeclampsia (AOR 1.38, 95%CI 1.05–1.81) and genitourinary infection (AOR 1.32, 95% CI 1.11–1.57).

Both early pregnancy warm weather exposure and neighborhood vulnerability independently increased the risk of adverse maternal complications. Our findings provide evidence in support of targeted heat mitigation strategies to limit heat exposure in at-risk communities as climate change progresses.