Exposure to seasonal temperatures during the last month of gestation and the risk of preterm birth in Stockholm.

Ana Vicedo-Cabrera,Bertil Forsberg,David Olsson

doi:10.3390/ijerph120403962

Ana Vicedo-Cabrera, Bertil Forsberg + Show 1 more

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https://doi.org/10.3390/ijerph120403962

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Abstract

Recent evidence from studies performed mainly in warm climates suggests an association between exposure to extreme temperatures late in pregnancy and an increased risk of preterm delivery. However, there have been fewer studies on the effect of low temperatures. The aim of this study is to explore the potential association between both heat and cold during late pregnancy and an increased risk of preterm birth in the northern location of Stockholm, Sweden. All singleton spontaneous births that took place in greater Stockholm (1998–2006) were included. Non-linear and delayed effects of mean temperature on the risk of preterm birth were explored through distributed lag non-linear models. Extreme and moderate heat and cold were estimated separately through quasi-Poisson regression analysis in two seasonal periods (heat in warm season, cold in cold season). The risk of preterm birth increased by 4%–5% when the mean temperature reached the 75th percentile (moderate heat) four weeks earlier (reference: the annual median value), with a maximum cumulative risk ratio of 2.50 (95% confidence interval: 1.02–6.15). Inconsistent associations were obtained for cold and extreme heat. Exposure to moderately high temperatures during late pregnancy might be associated with an increase in risk of preterm birth in Stockholm.

Highlights

Effects of climate change on population health have barely been investigated but are a major public health concern
This study explored the association between the risk of preterm birth and the exposure to heat and cold during late pregnancy in a northern population in Europe
Our results suggest that exposure to moderate heat during the previous four weeks before the delivery might be associated with an increased risk of giving birth prematurely

Summary

Introduction

Effects of climate change on population health have barely been investigated but are a major public health concern. One of the emerging research issues gaining attention is the effect of exposure to high or low temperatures during pregnancy. A few recent studies addressed the potential association between the exposure to extreme temperatures and different birth outcomes, including preterm birth, low birth weight, stillbirth, and congenital anomalies [1,2,3,4,5,6,7,8,9]. It is known that pregnant women might be more susceptible to temperature extremes due to the extra physical and mental strain of pregnancy and their limited ability to maintain temperature balance [10,11]. The fetus has a limited ability to regulate temperature, and it is entirely dependent upon the mother’s thermoregulatory capacity [12]. To date the population of pregnant women has not been yet considered as a vulnerable group in the current Heat Health Warning Systems in force

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