Associations between ambient air temperature, low birth weight and small for gestational age in term neonates in southern Israel

Itai Kloog,Allan C. Just,Lena Novack,Offer Erez,Raanan Raz

doi:10.1186/s12940-018-0420-z

Abstract

BackgroundThe increase in ambient temperatures (Ta) and emissions of greenhouse gases over the last century has focused attention on the effects of ambient temperatures on health outcomes. We aimed to investigate the association between Ta and the clinical measures of term low birth weight (tLBW) and small for gestational age (SGA) in singleton term infants using a decade of regional hospital data in southern Israel.MethodsWe linked all births in Soroka University Medical Center in the southern district of Israel insured by Clalit Health Services with pregnancy Ta estimated by our novel hybrid spatio-temporally resolved prediction model. Logistic regression generalized additive models and general linear models were used, with either tLBW or SGA as the dependent variable, modeling entire pregnancy and trimester-specific Ta adjusting for seasonality, time trend, particulate matter, maternal age, gravidity, parity, ethnicity, sex, poverty index and population density.ResultsThe study population included 56,141 singleton term newborns, with 1716 (3.1%) cases of tLBW and 8634 (15.4%) cases of SGA. The average and the median Ta across the entire pregnancy were 19.9 (SD: 1.77, range: 14.6–24.9) degrees centigrade. The lowest Ta quartile (Ta = < 18.5) was associated with higher risk of tLBW (odds ratio = 1.33, 95%CI 1.11–1.58) while the highest Ta quartile (Ta > =21.3) was not significantly associated with tLBW (odds ratio = 1.17, 95%CI 0.99–1.38), in comparison to the two intermediate quartiles. When analyzing SGA as the dependent variable, the lowest Ta quartile was associated with significantly higher risk of SGA (odds ratio = 1.18, 95%CI 1.09–1.29) while the highest quartile was associated with significantly lower risk of SGA (odds ratio = 0.91, 95%CI 0.84–0.99) in comparison to the two intermediate quartiles.ConclusionsOur findings suggest that lower pregnancy Ta may increase the risk of tLBW and SGA, and higher pregnancy Ta may decrease the risk of SGA in singleton term infants in southern Israel.

Highlights

The rise in temperatures over the last century and emissions of greenhouse gases has focused attention on the effects of increasing heat [1]
When analyzing small for gestational age (SGA) as the dependent variable, the lowest Ta quartile was associated with significantly higher risk of SGA (OR = 1.18, 95%CI 1.09–1.29) while the highest quartile was associated with significantly lower risk of SGA (OR = 0.91, 95%CI 0.84–0.99) in comparison to the two intermediate quartiles (Table 2)
When examining associations among term low birth weight (tLBW), SGA and trimester-specific Ta exposures, we found decreased risk of SGA with high Ta quartile during the 1st trimester (OR = 0.82, 95%CI 0.73–0.92), and increased risk for

Summary

Introduction

The rise in temperatures over the last century and emissions of greenhouse gases has focused attention on the effects of increasing heat [1]. Kloog et al Environmental Health (2018) 17:76 mortality rates recorded at moderate temperatures, rising progressively as temperatures increase or decrease [7, 10, 13]. These studies have shown that the effects of temperature vary geographically [15, 16] and depend on local climatic conditions and population characteristics such as demography, socioeconomic conditions and health status [3]. We aimed to investigate the association between Ta and the clinical measures of term low birth weight (tLBW) and small for gestational age (SGA) in singleton term infants using a decade of regional hospital data in southern Israel

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