Temperature and birth weight in Latin American cities

BAKHTSIYARAVA, MARYIA ; ORTIGOZA, ANA; BRAVERMAN, ARIELA; KEPHART, JOSIAH; RODRÍGUEZ LÓPEZ, SANTIAGO; RODRIGUEZ HERNANDEZ, JORDAN; DIEZ-ROUX, ANA V.; SÁNCHEZ, BRISA

Modalidad virtual

Congreso; 17th International Conference on Urban Health; 2021

International Society for Urban Health

Background: Extreme temperatures can lead to adverse pregnancy and birth outcomes (peripartum complications, preterm delivery, low birth weight, and stillbirth). Studies on the impact of temperature on birth weight have been inconclusive due to methodological challenges related to operationalizing temperature exposure, the definitions of exposure windows, accounting for gestational age, and a limited geographic scope.Methods: We combined data on individual-level live births (N ≈ 25 million births) from urban areas in Brazil, Chile, and Mexico from 2005-2015 from the SALURBAL study (Urban Health in Latin America) with high-resolution daily temperature data. We examined associations between full-term birth weight and the number of hot and cold days, as well as mean daily temperature, during relevant exposure windows for every live birth using mixed-effects linear models. The models controlled for child- and mother-level biological and socioeconomic characteristics, cohort effects, and climate zone.Results: Every additional hot day during pregnancy is associated with a 0.11-gram decrease [95% CI = -0.21, -0.02] in birth weight. An additional hot day during the last trimester is associated with a 0.26-gram decrease [95% CI = -0.38, -0.13] in birth weight. Cold days did not show statistically significant associations with birth weight during the entire pregnancy and during the various exposure windows. For mean daily temperature, we found no association with birth weight during the entire pregnancy and found inconsistent associations during the trimesters. Conclusion: The associations between temperature and birth weight are small in magnitude and sensitive to the way temperature exposure is measured.