Associations Between High Temperatures in Pregnancy and Risk of Preterm Birth, Low Birth Weight, and Stillbirths: Systematic Review and Meta-analysis

Overview

Journal BMJ

Specialty General Medicine

Date 2020 Nov 5

PMID 33148618

Citations 134

Authors

Matthew Francis Chersich

Minh Duc Pham

Ashtyn Areal

Marjan Mosalam Haghighi

Albert Manyuchi

Callum P Swift

Bianca Wernecke

Matthew Robinson

Robyn Hetem

Melanie Boeckmann

Shakoor Hajat

Affiliations

Soon will be listed here.

Abstract

Objective: To assess whether exposure to high temperatures in pregnancy is associated with increased risk for preterm birth, low birth weight, and stillbirth.

Design: Systematic review and random effects meta-analysis.

Data Sources: Medline and Web of Science searched up to September 2018, updated in August 2019.

Eligibility Criteria For Selecting Studies: Clinical studies on associations between high environmental temperatures, and preterm birth, birth weight, and stillbirths.

Results: 14 880 records and 175 full text articles were screened. 70 studies were included, set in 27 countries, seven of which were countries with low or middle income. In 40 of 47 studies, preterm births were more common at higher than lower temperatures. Exposures were classified as heatwaves, 1°C increments, and temperature threshold cutoff points. In random effects meta-analysis, odds of a preterm birth rose 1.05-fold (95% confidence interval 1.03 to 1.07) per 1°C increase in temperature and 1.16-fold (1.10 to 1.23) during heatwaves. Higher temperature was associated with reduced birth weight in 18 of 28 studies, with considerable statistical heterogeneity. Eight studies on stillbirths all showed associations between temperature and stillbirth, with stillbirths increasing 1.05-fold (1.01 to 1.08) per 1°C rise in temperature. Associations between temperature and outcomes were largest among women in lower socioeconomic groups and at age extremes. The multiple temperature metrics and lag analyses limited comparison between studies and settings.

Conclusions: Although summary effect sizes are relatively small, heat exposures are common and the outcomes are important determinants of population health. Linkages between socioeconomic status and study outcomes suggest that risks might be largest in low and middle income countries. Temperature rises with global warming could have major implications for child health.

Systematic Review Registration: PROSPERO CRD 42019140136 and CRD 42018118113.

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References

Strand L, Barnett A, Tong S . The influence of season and ambient temperature on birth outcomes: a review of the epidemiological literature. Environ Res. 2011; 111(3):451-62. DOI: 10.1016/j.envres.2011.01.023. View

Zheng X, Zhang W, Lu C, Norback D, Deng Q . An epidemiological assessment of the effect of ambient temperature on the incidence of preterm births: Identifying windows of susceptibility during pregnancy. J Therm Biol. 2018; 74:201-207. DOI: 10.1016/j.jtherbio.2018.04.001. View

Beltran A, Wu J, Laurent O . Associations of meteorology with adverse pregnancy outcomes: a systematic review of preeclampsia, preterm birth and birth weight. Int J Environ Res Public Health. 2013; 11(1):91-172. PMC: 3924438. DOI: 10.3390/ijerph110100091. View

MacVicar S, Berrang-Ford L, Harper S, Huang Y, Bambaiha D, Yang S . Whether weather matters: Evidence of association between in utero meteorological exposures and foetal growth among Indigenous and non-Indigenous mothers in rural Uganda. PLoS One. 2017; 12(6):e0179010. PMC: 5462429. DOI: 10.1371/journal.pone.0179010. View

Carmichael S, Cullen M, Mayo J, Gould J, Loftus P, Stevenson D . Population-level correlates of preterm delivery among black and white women in the U.S. PLoS One. 2014; 9(4):e94153. PMC: 3989227. DOI: 10.1371/journal.pone.0094153. View

Weng Y, Yang C, Chiu Y . Adverse neonatal outcomes in relation to ambient temperatures at birth: A nationwide survey in Taiwan. Arch Environ Occup Health. 2017; 73(1):48-55. DOI: 10.1080/19338244.2017.1299084. View

Ngo N, Horton R . Climate change and fetal health: The impacts of exposure to extreme temperatures in New York City. Environ Res. 2015; 144(Pt A):158-164. DOI: 10.1016/j.envres.2015.11.016. View

PORTER K, Thomas S, Whitman S . The relation of gestation length to short-term heat stress. Am J Public Health. 1999; 89(7):1090-2. PMC: 1508861. DOI: 10.2105/ajph.89.7.1090. View

Rammah A, Whitworth K, Han I, Chan W, Wendt Hess J, Symanski E . Temperature, placental abruption and stillbirth. Environ Int. 2019; 131:105067. PMC: 11024926. DOI: 10.1016/j.envint.2019.105067. View

10.

Lin Y, Hu W, Xu J, Luo Z, Ye X, Yan C . Association between temperature and maternal stress during pregnancy. Environ Res. 2017; 158:421-430. DOI: 10.1016/j.envres.2017.06.034. View

11.

Elter K, Ay E, Uyar E, Kavak Z . Exposure to low outdoor temperature in the midtrimester is associated with low birth weight. Aust N Z J Obstet Gynaecol. 2004; 44(6):553-7. DOI: 10.1111/j.1479-828X.2004.00314.x. View

12.

Krstic G . Apparent temperature and air pollution vs. elderly population mortality in Metro Vancouver. PLoS One. 2011; 6(9):e25101. PMC: 3182192. DOI: 10.1371/journal.pone.0025101. View

13.

Wu M, Song L, Zheng X, Zhang L, Liu B, Wang L . Prenatal exposure of diurnal temperature range and preterm birth: Findings from a birth cohort study in China. Sci Total Environ. 2019; 656:1102-1107. DOI: 10.1016/j.scitotenv.2018.11.305. View

14.

He J, Liu Y, Xia X, Ma W, Lin H, Kan H . Ambient Temperature and the Risk of Preterm Birth in Guangzhou, China (2001-2011). Environ Health Perspect. 2015; 124(7):1100-6. PMC: 4937853. DOI: 10.1289/ehp.1509778. View

15.

Wells J, Cole T . Birth weight and environmental heat load: a between-population analysis. Am J Phys Anthropol. 2002; 119(3):276-82. DOI: 10.1002/ajpa.10137. View

16.

Auger N, Fraser W, Smargiassi A, Bilodeau-Bertrand M, Kosatsky T . Elevated outdoor temperatures and risk of stillbirth. Int J Epidemiol. 2016; 46(1):200-208. PMC: 5837696. DOI: 10.1093/ije/dyw077. View

17.

Ho J . Early-Life Environmental Exposures and Height, Hypertension, and Cardiovascular Risk Factors Among Older Adults in India. Biodemography Soc Biol. 2015; 61(2):121-46. PMC: 4545224. DOI: 10.1080/19485565.2015.1045580. View

18.

Luton D, Alran S, Fourchotte V, Sibony O, Oury J . Paris heat wave and oligohydramnios. Am J Obstet Gynecol. 2004; 191(6):2103-5. DOI: 10.1016/j.ajog.2004.05.090. View

19.

Davis R, Novicoff W . The Impact of Heat Waves on Emergency Department Admissions in Charlottesville, Virginia, U.S.A. Int J Environ Res Public Health. 2018; 15(7). PMC: 6068980. DOI: 10.3390/ijerph15071436. View

20.

Fukuda M, Fukuda K, Shimizu T, Nobunaga M, Mamsen L, Andersen C . Climate change is associated with male:female ratios of fetal deaths and newborn infants in Japan. Fertil Steril. 2014; 102(5):1364-1370.e2. DOI: 10.1016/j.fertnstert.2014.07.1213. View