Birth Weight in a Warming World: Is the 'Healthy Immigrant Effect' a Protective Factor against Extreme Heat?

Teresa Castro , CSIC
Héctor Cebolla, CSIC
Teresa Martin Garcia, Spanish Council for Scientific Research
Amparo Gonzalez-Ferrer, Consejo Superior de Investigaciones Científicas (CSIC)

Research into the relationship between migration and health often centers around the so-called "healthy immigrant paradox." This paradox hinges on the observation that, despite their higher levels of socioeconomic vulnerability, migrants exhibit, on average, better health outcomes than native populations. This advantage includes better perinatal and birth outcomes. Recent literature has also assessed the impact of extreme heat on maternal and perinatal health. Bridging these two strands of literature, our central research question is: Can the health advantage observed among migrants offset the adverse impact of exposure to extreme heat on birth weight? We compiled a dataset by merging birth register data from 2018 to 2021 in Spain (1,201,585 births, of which 299,643 correspond to immigrant mothers) and climate records from the National Meteorology Agency in order to analyze the relationship between birth weight and the number of “orange alarm” days (>37ºC) in the province of birth. These data allow to explore the interplay between migrant status and extreme heat on birth weight (VLBW [<1,500 g], LBW [<2,500 g] and macrosomia [>4,000 g]). Controls in our model include: maternal age, education, activity, and occupational type, paternal presence, and newborn’s sex. We employed two distinct modeling approaches: linear probability models and quantile regression. Our preliminary results indicate that exposure to extreme heat has a negative impact on birth outcomes across migrant status. Therefore, it appears that the “healthy immigrant effect” does not provide protection to babies of migrant origin against the adverse effects of exposure to extreme weather conditions during gestation.

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 Presented in Session P2. Health, Mortality, Ageing - Aperitivo