Evidence suggests that heat exposure increases delivery risk for pregnant women. Acceleration of childbirth leads to shorter gestation, which has been linked to later health and cognitive outcomes. However, estimates of the aggregate gestational losses resulting from hot weather are lacking in the literature. Here, we use estimated shifts in daily county birth rates to quantify the gestational losses associated with heat in the United States from 1969 to 1988. We find that extreme heat causes an increase in deliveries on the day of exposure and on the following day and show that the additional births were accelerated by up to two weeks. We estimate that an average of 25,000 infants per year were born earlier as a result of heat exposure, with a total loss of more than 150,000 gestational days annually. Absent adaptation, climate projections suggest additional losses of 250,000 days of gestation per year by the end of the century.
Subscribe to Journal
Get full journal access for 1 year
only $17.75 per issue
All prices are NET prices.
VAT will be added later in the checkout.
Rent or Buy article
Get time limited or full article access on ReadCube.
All prices are NET prices.
All data necessary for replication of the results in this paper are available for download at https://figshare.com/s/c984d29316e012b79e32. The original weather data can be downloaded from ftp://ftp.ncdc.noaa.gov/pub/data/ghcn/daily. The original birth records can be downloaded from http://www.nber.org/natality/. The population data can be downloaded from https://seer.cancer.gov/popdata/download.html. Interested researchers should contact Urs Beyerle or Jan Sedlacek at ETH Zurich to gain access to the CMIP5 climate projection data. Source data for Figs. 1–4 are provided with the paper.
The code necessary for replication of the results in this paper is available for download at https://figshare.com/s/c984d29316e012b79e32.
Poursafa, P., Keikha, M. & Kelishadi, R. Systematic review on adverse birth outcomes of climate change. J. Res. Med. Sci. 20, 397–402 (2015).
Figlio, D. N., Guryan, J., Karbownik, K. & Roth, J. Long-term cognitive and health outcomes of school-aged children who were born late-term vs full-term. JAMA Pediatr. 170, 758–764 (2016).
Spong, C. Y. Defining “term” pregnancy: recommendations from the Defining “Term” Pregnancy Workgroup. JAMA 309, 2445–2446 (2013).
Almond, D. & Currie, J. Killing me softly: the fetal origins hypothesis. J. Econ. Perspect. 25, 153–172 (2011).
Tao, S., Monteiro, A. P. A., Thompson, I. M., Hayen, M. J. & Dahl, G. E. Effect of late-gestation maternal heat stress on growth and immune function of dairy calves. J. Dairy Sci. 95, 7128–7136 (2012).
Dreiling, C. E., Carman, F. S. & Brown, D. E. Maternal endocrine and fetal metabolic responses to heat stress. J. Dairy Sci. 74, 312–327 (1991).
Fuchs, A., Fuchs, F., Husslein, P., Soloff, M. S. & Fernstrom, M. J. Oxytocin receptors and human parturition: a dual role for oxytocin in the initiation of labor. Science 215, 1396–1398 (1982).
Hampel, R. et al. Short-term impact of ambient air pollution and air temperature on blood pressure among pregnant women. Epidemiology 22, 671–679 (2011).
Strand, L. B., Barnett, A. G. & Tong, S. Maternal exposure to ambient temperature and the risks of preterm birth and stillbirth in Brisbane, Australia. Am. J. Epidemiol. 175, 99–107 (2011).
Auger, N., Naimi, A. I., Smargiassi, A., Log, E. & Kosatsky, T. Extreme heat and risk of early delivery among preterm and term pregnancies. Epidemiology 25, 344–350 (2014).
Avalos, L. A., Chen, H., Li, D. & Basu, R. The impact of high apparent temperature on spontaneous preterm delivery: a case-crossover study. Environ. Health 16, 5 (2017).
Basu, R., Malig, B. & Ostro, B. High ambient temperature and the risk of preterm delivery. Am. J. Epidemiol. 172, 1108–1117 (2010).
Dadvand, P. et al. Climate extremes and the length of gestation. Environ. Health Perspect. 119, 1449–14453 (2011).
Lee, S. J., Hajat, S., Steer, P. J. & Filippi, V. A time-series analysis of any short-term effects of meteorological and air pollution factors on preterm births in London, UK. Environ. Res. 106, 185–194 (2008).
Porter, K. R., Thomas, S. D. & Whitman, S. The relation of gestation length to short-term heat stress. Am. J. Public Health 89, 1090–1092 (1999).
Schifano, P. et al. Effect of ambient temperature and air pollutants on the risk of preterm birth, Rome 2001–2010. Environ. Int. 61, 77–87 (2013).
Vicedo-Cabrera, A. M., Iniguez, C., Barona, C. & Ballester, F. Exposure to elevated temperatures and risk of preterm birth in Valencia, Spain. Environ. Res. 134, 210–217 (2014).
Yackerson, N., Piura, B. & Sheiner, E. The influence of meteorological factors on the emergence of preterm delivery and preterm premature rupture of membrane. J. Perinatol. 28, 707–711 (2008).
Strand, L. B., Barnett, A. G. & Tong, S. The influence of season and ambient temperature on birth outcomes: a review of the epidemiological literature. Environ. Res. 111, 451–462 (2011).
Song, X. et al. Impact of ambient temperature on morbidity and mortality: an overview of reviews. Sci. Total Environ. 586, 241–254 (2017).
Barreca, A., Deschenes, O. & Guldi, M. Maybe next month? Temperature shocks and dynamic adjustments in birth rates. Demography 55, 1269–1293 (2018).
IPCC Climate Change 2014: Synthesis Report (eds Core Writing Team, Pachauri, R. K. & Meyer, L. A.) (IPCC, 2014).
Lynch, C. D. & Zhang, J. The research implications of the selection of a gestational age estimation method. Paediatr. Perinat. Epidemiol. 21, 86–96 (2007).
Dell, M., Jones, B. F. & Olken, B. A. What do we learn from the weather? The new climate–economy literature. J. Econ. Lit. 52, 740–798 (2014).
Obradovich, N., Migliorini, R., Mednick, S. C. & Fowler, J. H. Nighttime temperature and human sleep loss in a changing climate. Sci. Adv. 3, e1601555 (2017).
Barreca, A., Clay, K., Deschenes, O., Greenstone, M. & Shapiro, J. S. Adapting to climate change: the remarkable decline in the US temperature–mortality relationship over the twentieth century. J. Polit. Econ. 124, 105–159 (2016).
Isen, A., Rossin-Slater, M. & Walker, R. Relationship between season of birth, temperature exposure, and later life wellbeing. Proc. Natl Acad. Sci. USA 114, 13447–13452 (2017).
Biddle, J. Explaining the spread of residential air conditioning, 1955–1980. Explor. Econ. Hist. 45, 402–423 (2008).
Taylor, K. E., Stouffer, R. J. & Meehl, G. A. An overview of CMIP5 and the experiment design. Bull. Am. Meteorol. Soc. 93, 485–498 (2012).
Deschênes, O., Greenstone, M. & Guryan, J. Climate change and birth weight. Am. Econ. Rev. 99, 211–217 (2009).
We acknowledge the World Climate Research Programme’s Working Group on Coupled Modelling, which is responsible for CMIP, and we thank the climate modelling groups for producing and making available their model output. We are grateful for U. Beyerle and J. Sedlacek at ETH Zurich, who provided access to the CMIP data. This research was supported by funding from the California Strategic Growth Council Climate Change Research Program (no. CCRP0056). P. Stainier provided valuable research assistance.
The authors declare no competing interests.
Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Temperature-Dose Response Function on Day 0
Effect of Daily Maximum Temperature ≥90 °F on Birth Rates, by Days from Exposure. a: Distributed lag coefficients; b: cumulative effects
Heterogeneous Effects of Daily Max Temperature ≥90 °F on Birth Rates
Modifying effect of air conditioning
About this article
Cite this article
Barreca, A., Schaller, J. The impact of high ambient temperatures on delivery timing and gestational lengths. Nat. Clim. Chang. (2019) doi:10.1038/s41558-019-0632-4