Maximum apparent temperature lowers birth weight and increase hazards of preterm birth in a constant high ambient temperature exposed population in Piura, Peru

Abstract

Background and aim: Exposure to high environmental temperature during pregnancy has been associated with lower birth weight and an increased risk of preterm birth (PTB). The province of Piura is a region with a higher environmental temperature than the rest of the country; however, it is unknown how temperature would be impacting reproductive health in populations exposed to high basal temperatures. The aim of the study is to determine the association between maximum apparent temperature (HImax) during pregnancy with birth weight and preterm birth in newborns in the province of Piura, 2011-2016. Method: Semi-ecological study, where maternal-perinatal data from Santa Rosa Hospital (N=17,788); and maximum apparent temperature data were evaluated. Four exposure windows were analyzed: the entire pregnancy, and each gestational trimester, which were assigned according to date of birth and gestational age, categorized into quartiles. The association with birth weight was assessed by linear regression; and Cox regression for PTB. Results: A negative association was found between birth weight and HImax in all exposure windows, except for the first trimester, the effect being greater during the third trimester. As for preterm birth, higher HImax increased the hazard of PTB, with the highest effect seen in the P95 exposed group in every exposure window; nonetheless, the first and second trimester being the most temperature-sensitive exposure windows. Conclusions: HImax during pregnancy is related to lower birth weight and higher PTB hazards, but with different susceptibility according to the stage of pregnancy. Keywords: Apparent Temperature, Heat Index, Birth Outcomes, Peru, Latin America