50 Associations Between Maternal Extreme Heat Exposure and Inflammatory Biomarkers in Early and Late Pregnancy

Maternal heat exposure has been linked to adverse pregnancy outcomes. The impact of high ambient temperature exposure on inflammation during human pregnancy remains largely unknown. Determine the associations between preconception/ trimester-wise exposure to excessive heat stress (HS) and α1-acid glycoprotein (AGP) or C-Reactive Protein (CRP) at 12 and 34 weeks of gestation. This secondary analysis included women with serum concentrations of AGP (n = 160), and CRP (n = 143) collected at 12 and 34 weeks of pregnancy from Women First Preconception Maternal Nutrition Trial in Thatta, Pakistan. Excessive HS was categorically defined as > 20 days with average maximal daily temperature >39 °C in each period: 90 days preconception (PreC), trimester 1 (T1), or trimester 2 (T2). Multiple linear regression was used to assess relationships between HS and each inflammatory marker in separate models for 12 and 34-weeks assessments, including adjustment for maternal characteristics, intervention arm, cluster, maternal anemia status, PM2.5 levels, and 12-week AGP or CRP (for 34-week outcomes). Exposure to HS during PreC increased 34-week AGP by 0.10 µg/mL compared to no HS exposure (p = 0.045). Exposure to HS compared to no exposure was positively associated with 34-week CRP (mg/L) during PreC (ß= 1.90, p = 0.015), T1 (ß= 2.06, p = 0.009), and T2 (ß= 1.93, p = 0.020). No significant associations were observed between exposure to HS and inflammatory markers at 12 weeks. Findings suggest that preconception and early pregnancy HS may contribute to late-gestation inflammation.