Ambient Temperature and Early Delivery of Singleton Pregnancies

Ha, Sandie; Liu, Danping; Zhu, Yeyi; Kim, Sung Soo; Sherman, Seth; Mendola, Pauline

doi:10.1289/ehp97

Cited by 92 publications

(92 citation statements)

References 31 publications

(45 reference statements)

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“…In the past few decades, an increasing number of epidemiological studies have evaluated the influence of temperature exposure during pregnancy on PTB (Barreca and Schaller 2019;Carolan-Olah and Frankowska 2014;Guo et al 2018;Zhang et al 2017) and other adverse birth outcomes such as birth defects (Soim et al 2017). Most studies suggested an association between high-temperature exposure during the week prior to the delivery and PTB (Basu et al 2010;Ha et al 2017). Relationships between heatwaves (based on an indicator combining both the heat intensity and duration of heat exposure) and PTB have not been studied as extensively.…”

Section: Discussionmentioning

confidence: 99%

Independent and Combined Effects of Heatwaves and PM2.5 on Preterm Birth in Guangzhou, China: A Survival Analysis

Wang

Benmarhnia

et al. 2020

Environ Health Perspect

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BACKGROUND: Both extreme heat and air pollution exposure during pregnancy have been associated with preterm birth; however, their combined effects are unclear. OBJECTIVES: Our goal was to estimate the independent and joint effects of heatwaves and fine particulate matter [PM <2:5 lm in aerodynamic diameter (PM 2:5 )], exposure during the final gestational week on preterm birth. METHODS: Using birth registry data from Guangzhou, China, we included 215,059 singleton live births in the warm season (1 May-31 October) between January 2015 and July 2017. Daily meteorological variables from 5 monitoring stations and PM 2:5 concentrations from 11 sites were used to estimate district-specific exposures. A series of cut off temperature thresholds and durations (2, 3, and 4 consecutive d) were used to define 15 different heatwaves. Cox proportional hazard models were used to estimate the effects of heatwaves and PM 2:5 exposures during the final week on preterm birth, and departures from additive joint effects were assessed using the relative excess risk due to interaction (RERI). RESULTS: Numbers of preterm births increased in association with heatwave exposures during the final gestational week. Depending on the heatwave definition used, hazard ratios (HRs) ranged from 1.10 (95% CI: 1.01, 1.20) to 1.92 (1.39, 2.64). Associations were stronger for more intense heatwaves. Combined effects of PM 2:5 exposures and heatwaves appeared to be synergistic (RERIs >0) for less extreme heatwaves (i.e., shorter or with relatively low temperature thresholds) but were less than additive (RERIs <0) for more intense heatwaves. CONCLUSIONS: Our research strengthens the evidence that exposure to heatwaves during the final gestational week can independently trigger preterm birth. Moderate heatwaves may also act synergistically with PM 2:5 exposure to increase risk of preterm birth, which adds new evidence to the current understanding of combined effects of air pollution and meteorological variables on adverse birth outcomes. https://doi.

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Section: Discussionmentioning

confidence: 99%

Independent and Combined Effects of Heatwaves and PM2.5 on Preterm Birth in Guangzhou, China: A Survival Analysis

Wang

Benmarhnia

et al. 2020

Environ Health Perspect

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“…The effect of meteorological factors on preterm birth incidence is an important topic of global interest and has been previously approached in several recent studies [ 6 ]. Seasonal weather changes are known to have an important effect on the overall human morbidity especially for the infectious and cardiovascular diseases [ 17 ], but the influence that it may have on the pregnancy outcomes is still a topic of debate [ 18 ].…”

Section: Discussionmentioning

confidence: 99%

The influence of seasonality and weather changes on premature birth incidence

Mureşan

Staicu

Zaharie

et al. 2017

Medicine and Pharmacy Reports

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BackgroundAlthough the effects of meteorological factors on the general population health are widely documented, little is known about their influence on human pregnancy and birth. The present study aims at analyzing the influence of the atmospheric conditions on premature births.MethodOne hundred and eight nine cases of premature births were included in the study, with a gestational age between 24 to 37 weeks of amenorrhea. Cases with antepartum fetal death and those with uncertain gestational age have been excluded. Daily weather data were obtained using http://www.wunderground.com site.A Pearson’s product-moment correlation was run to assess the relationship between weekly preterm birth incidence and the total number of premature births and the mean maximum and minimum temperature (Tmax, Tmin), maximum and minimum average humidity (Umax, Umin), maximum and minimum atmospheric pressure mean (P max, P min), average wind speed and average quantity precipitations, calculated for one calendar week.ResultsApproximately 7.7% of all births during the study period occurred before 37 weeks of gestation, the main reason for hospitalization being premature rupture of membranes (45%). The analysis revealed a moderate positive correlation between weekly preterm birth incidence and the average temperature (r=0.306, n=52, p=0.027) and a moderate positive correlation between weekly preterm birth incidence and temperature variation (r=0.307, n=52, p=0.007). Our study found no significant statistic correlation between the humidity variation, pressure variation, and wind speed.ConclusionsThe incidence of premature births can be influenced by variations of specific weather factors, especially during the weeks characterized by large fluctuations in temperature. The results obtained might inspire the construction of multicenter studies to investigate more thoroughly the adverse effects of some meteorological factors that can influence the outcomes of human pregnancy.

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“…Case-crossover analysis is commonly used in studies of PTB and temperature 12 13 34. Because PTB is not a rare event in this particular population, the case-crossover ORs would not approximate risk ratios.…”

Section: Methodsmentioning

confidence: 99%

“…Studies in cities in Australia, Quebec, China, Belgium, Italy, Spain and across the USA have all found significant positive associations between hot temperatures within the week preceding delivery and PTB. 5 6 8–16 High ambient temperatures in the month of conception and the third trimester were also positively associated with PTB in Changsha, China 17 18. However, earlier, rigorously conducted time series analyses of temperature and PTB in Germany and in London, England, did not find associations 19 20.…”

Section: Introductionmentioning

confidence: 95%

“…Likewise, in Chicago, Illinois, Porter et al found no effect of the July 1995 heat wave on gestational length 21. Sources of heterogeneity among these effect estimates may include differences in study design, prevailing climate and regional adaptation, population structure, exposure assessment, critical windows of exposure considered and methods of gestational age assessment 12…”

Section: Introductionmentioning

confidence: 99%

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Time series analysis of total and direct associations between high temperatures and preterm births in Detroit, Michigan

et al. 2020

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ObjectivesPreterm births (PTBs) represent significant health risks, and several studies have found associations between high outdoor temperatures and PTB. We estimated both the total and natural direct effects (independent of particulate matter, ozone and nitrogen dioxide air pollutants) of the prior 2-day mean apparent temperature (AT) on PTB. We evaluated effect modification by maternal age, race, education, smoking status and prenatal care.Design and settingWe obtained birth records and meteorological data for the Detroit, Michigan, USA area, for the warm months (May to September), 1991 to 2001. We used a time series Poisson regression with splines of AT, wind speed, solar radiation and citywide average precipitation to estimate total effects. To accommodate multiple mediators and exposure-mediator interactions, AT inverse odds weights, predicted by meteorological and air pollutant covariates, were added in a subsequent model to estimate direct effects.ResultsAt 24.9°C relative to 18.6°C, 10.6% (95% CI: 3.8% to 17.2%) of PTBs were attributable to the total effects of AT, and 10.4% (95% CI: 2.2% to 17.5%) to direct effects. Relative excess risks of interaction indicated that the risk of PTB with increasing temperature above 18.6°C was significantly lower among black mothers and higher among mothers less than 19, older than 30, with late or no prenatal care and who smoked.ConclusionThis additional evidence of a direct association between high temperature and PTB may motivate public health interventions to reduce extreme heat exposures among pregnant women, particularly among those who may have enhanced vulnerability.

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Ambient Temperature and Early Delivery of Singleton Pregnancies

Cited by 92 publications

References 31 publications

Independent and Combined Effects of Heatwaves and PM2.5 on Preterm Birth in Guangzhou, China: A Survival Analysis

Independent and Combined Effects of Heatwaves and PM2.5 on Preterm Birth in Guangzhou, China: A Survival Analysis

The influence of seasonality and weather changes on premature birth incidence

Time series analysis of total and direct associations between high temperatures and preterm births in Detroit, Michigan

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