Association between Prenatal, Pre-pregnancy Rainfall and Adult Obesity: Findings from the Community Behavior and Attitude Survey in Tuvalu (COMBAT)

Tuvalu has one of the highest obesity prevalence rates globally, and is a Pacific Island nation facing significant climate change challenges. Altered rainfall pattern, as a part of climate change, may influence obesity risk during the critical developmental periods. This study investigated the associations between rainfall exposure during prenatal, pre-pregnancy periods and adult obesity in Tuvalu. A nationwide survey was conducted between February and May 2022, which included 892 adults from Tuvalu. Rainfall data was obtained from ECMWF Reanalysis v5 based on participants’ birth year and birthplace. Rainfall exposure during the first year of birth, the year before birth, and two years before birth was analyzed, and rainfall exposure between three to five years before birth were included as negative control periods. Obesity and severe obesity were defined based on body mass index (BMI) upon the survey, according to the World Health Organization criteria. The results showed association between higher rainfall before birth increased BMI and greater odds of adulthood obesity. These associations were more pronounced among male participants. No significant associations were observed for rainfall three to five years before birth. In conclusion, prenatal exposure to higher rainfall during the year and two years before birth are associated with increased obesity risk in adulthood, reflecting prenatal environmental influences on developmental periods. These findings emphasize the importance of understanding climate-related health exposures and the need for targeted interventions in climate change-vulnerable populations. Further research should explore heterogeneity across Pacific Island nations and the mechanisms linking rainfall, birth weight, and obesity.