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Climate, Health, and Nutrition (Oral Session 9)

(OR09-03-25) Heat Exposure in Early Pregnancy Is Associated With Lower Linear Growth Characteristics From Birth to 2 Years

Sunday, June 1, 2025
4:24 PM – 4:36 PM ET
Location: S230 CD
Objectives: Heat stress during pregnancy has been shown to have detrimental effects on obstetric and neonatal outcomes. However, the impact of heat on child linear growth patterns has not been studied systematically. We examined associations between temperature during pregnancy trimesters and length-for-age z-scores (LAZ) until 2 y of age.

Methods: Data were collected as part of the Women First Preconception Nutrition Trial conducted in the Democratic Republic of Congo, Guatemala, India and Pakistan. Web-Bulb Globe Temperature (WBGT) was derived using ERA5-land reanalysis for each trimester and 3-month postnatal window until 9 months of age. Longitudinal LAZ (1, 3, 6, 12, 18 and 24 mo) was available for 2,104 mother-child pairs. We also estimated the magnitude and velocity of postnatal growth trajectory using SuperImposition by Translation And Rotation (SITAR). Linear mixed models adjusting for covariates were utilized to assess relationships between WBGT, LAZ outcomes and growth trajectory parameters.

Results: In linear mixed models adjusting for covariates, LAZ from birth to 24 mo was negatively associated with trimester 1 WBGTmax (ß/CI -0.03, -0.06 – 0.005, p=0.02) but not with WBGT in the 2nd or 3rd trimesters. The associations with trimester 1 WBGTmax remained significant after adjusting for LAZ at birth (ß/CI -0.03, -0.05 – 0.01, p< 0.001). Likewise, trimester 1 WBGTmax was nominally negatively associated with magnitude of SITAR length (ß/CI -0.007, -0.015 – 0.00, p=0.059), but not with length velocity. Postnatal WBGT values were not associated with LAZ at 12 or 24 months of age. However, WBGTmax between postnatal 3-6 mo was negatively associated with magnitude of SITAR length (ß/CI -0.008, -0.015 – 0.001, p=0.025).

Conclusions: Collectively, the findings indicate that in the setting of chronic malnutrition, thermal stress is associated with lower early childhood growth patterns, with early pregnancy being a particularly sensitive period.

Funding Sources: Bill & Melinda Gates Foundation, NIH/NICHD/ODS, USDA/ARS