Abstract
ABSTRACT: INTRODUCTION: 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. OBJECTIVE: 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. METHODS: 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, PM(2.5) levels, and 12-week AGP or CRP (for 34-week outcomes). RESULTS: 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. CONCLUSION: Findings suggest that preconception and early pregnancy HS may contribute to late-gestation inflammation.