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The goal of this study is to examine the association between in utero drought exposure and epigenetic age acceleration (EAA) in a global climate change hot spot. Calculations of EAA in adults using DNA methylation have been found to accurately predict chronic disease and longevity. However, fewer studies have examined EAA in children, and drought exposure in utero has not been investigated. Additionally, studies of EAA in low-income countries with diverse populations are rare. We assess EAA using epigenetic clocks and two DNAm-based pace-of-aging measurements from whole saliva samples in 104 drought-exposed children and 109 same-sex sibling controls in northern Kenya. We find a positive association between in utero drought exposure and EAA in two epigenetic clocks (Hannum's and GrimAge) and a negative association in the DNAm based telomere length (DNAmTL) clock. The combined impact of drought's multiple deleterious stressors may reduce overall life expectancy through accelerated epigenetic aging., (© 2024. The Author(s).)

Pastoralists in East Africa are among the world's most vulnerable communities to climate change, already living near their upper thermal limits and engaging in a climate-sensitive livelihood in a climate change global hot spot. Pregnant women and children are even more at risk. Here, we report the findings of a study characterizing Samburu pastoralist women's experiences of severe drought and outcomes in their children (N = 213, 1.8-9.6 y). First, we examined potential DNA methylation (DNAm) differences between children exposed to severe drought in utero and same-sex unexposed siblings. Next, we performed a high-dimensional mediation analysis to test whether DNAm mediated associations of exposure to severe drought with body weight and adiposity. DNAm was measured using the Infinium MethylationEPIC BeadChip array. After quality control; batch, chip, and genomic inflation corrections; covariate adjustment; and multiple testing correction, 16 CpG sites were differentially methylated between exposed and unexposed children, predominantly in metabolism and immune function pathways. We found a significant indirect effect of drought exposure on child body weight through cg03771070. Our results are the first to identify biological mediators linking severe drought to child growth in a low-income global hot spot for climate change. A better understanding of the mechanisms underlying the association between drought exposure and child growth is important to increasing climate change resilience by identifying targets for intervention.

Objectives: This study of Samburu pastoralists (Kenya) employs a same‐sex sibling design to test the hypothesis that exposure in utero to severe drought and maternal psychosocial stress negatively influence children's growth and adiposity. As a comparison, we also hypothesized that regional climate contrasts would influence children's growth and adiposity based on ecogeographical patterning. Materials and Methods: Anthropometric measurements were taken on Samburu children ages 1.8–9.6 years exposed to severe drought in utero and younger same‐sex siblings (drought‐exposed, n = 104; unexposed, n = 109) in two regions (highland, n = 128; lowland, n = 85). Mothers were interviewed to assess lifetime and pregnancy‐timed stress. Results: Drought exposure associated to lower weight‐for‐age and higher adiposity. Drought did not associate to tibial growth on its own but the interaction between drought and region negatively associated to tibial growth in girls. In addition, drought exposure and historically low rainfall associated to tibial growth in sensitivity models. A hotter climate positively associated to adiposity and tibial growth. Culturally specific stressors (being forced to work too hard, being denied food by male kin) associated to stature and tibial growth for age. Significant covariates for child outcomes included lifetime reported trauma, wife status, and livestock. Discussion: Children exposed in utero to severe drought, a hotter climate, and psychosocial stress exhibited growth differences in our study. Our results demonstrate that climate change may deepen adverse health outcomes in populations already psychosocially and nutritionally stressed. Our results also highlight the value of ethnography to identifying meaningful stressors. [ABSTRACT FROM AUTHOR]