Guest essay by Eric Worrall
The meta study notes at least one study which did not find a significant connection between heat exposure and premature birth, but the consensus appears to be black expectant mothers are especially at risk from global warming.
Climate crisis poses serious risks for pregnancy, investigation finds
Air pollution and heat exposure linked to negative outcomes
Researchers discover ‘pretty scary health burdens’
More than a decade of overwhelming evidence links air pollution and heat exposure with negative pregnancy outcomes in the US, according to a new review of dozens of studies.
The investigation, published in the Journal of the American Medical Association, identified 57 studies since 2007 showing a significant association between the two factors and the risk of pre-term birth, low birth weight and stillbirth.
Black mothers were particularly at risk, as were people with asthma.
The review analyzed 32m births tracked across 68 studies. Of those, 84% found air pollution and heat to be risk factors.
“When you talk about climate, people think about severe weather, big storms or huge fires … but we wanted to talk about the impacts that are common and widespread and ongoing and also are rarely attributed to the climate crisis,” said Bruce Bekkar, a co-author of the study and a retired obstetrician.
…Read more: https://www.theguardian.com/environment/2020/jun/18/climate-change-air-pollution-investigation-study
The abstract of the study;
June 18, 2020
Association of Air Pollution and Heat Exposure With Preterm Birth, Low Birth Weight, and Stillbirth in the USA Systematic Review
Importance Knowledge of whether serious adverse pregnancy outcomes are associated with increasingly widespread effects of climate change in the US would be crucial for the obstetrical medical community and for women and families across the country.
Objective To investigate prenatal exposure to fine particulate matter (PM2.5), ozone, and heat, and the association of these factors with preterm birth, low birth weight, and stillbirth.
Evidence Review This systematic review involved a comprehensive search for primary literature in Cochrane Library, Cochrane Collaboration Registry of Controlled Trials, PubMed, ClinicalTrials.gov website, and MEDLINE. Qualifying primary research studies included human participants in US populations that were published in English between January 1, 2007, and April 30, 2019. Included articles analyzed the associations between air pollutants or heat and obstetrical outcomes. Comparative observational cohort studies and cross-sectional studies with comparators were included, without minimum sample size. Additional articles found through reference review were also considered. Articles analyzing other obstetrical outcomes, non-US populations, and reviews were excluded. Two reviewers independently determined study eligibility. The Arskey and O’Malley scoping review framework was used. Data extraction was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) reporting guideline.
Findings Of the 1851 articles identified, 68 met the inclusion criteria. Overall, 32 798 152 births were analyzed, with a mean (SD) of 565 485 (783 278) births per study. A total of 57 studies (48 of 58 [84%] on air pollutants; 9 of 10 [90%] on heat) showed a significant association of air pollutant and heat exposure with birth outcomes. Positive associations were found across all US geographic regions. Exposure to PM2.5 or ozone was associated with increased risk of preterm birth in 19 of 24 studies (79%) and low birth weight in 25 of 29 studies (86%). The subpopulations at highest risk were persons with asthma and minority groups, especially black mothers. Accurate comparisons of risk were limited by differences in study design, exposure measurement, population demographics, and seasonality.
Conclusions and Relevance This review suggests that increasingly common environmental exposures exacerbated by climate change are significantly associated with serious adverse pregnancy outcomes across the US.Read more: https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2767260
From the body of the study;
Three studies44–46 examining large numbers of preterm births (range, 14 466-58 681 births) in California noted an increased risk of preterm birth for each 5.6 °C-increase in temperature, as did another study covering 12 clinical sites across the US for 2.8 °C increase.47
Two reports from California45,46 found an association of racial/ethnic disparity and heat exposure with an increasing risk of preterm birth; higher risk was found among black mothers. Increased risk of preterm birth was also found for Asian mothers and younger mothers in Basu et al.46
One cross-sectional analysis did not identify a significant association with preterm birth and heat exposure. Kloog et al’s48 satellite-based spatial modeling technique in Massachusetts found no association with preterm birth (1.04; 95% CI, 0.96-1.13) and a small reduction in gestational age at delivery (–0.26%; 95% CI, –0.28% to –0.25%) per 2.8 °C whole-pregnancy mean ambient temperature increase. Of note, standard monitoring data with similar elevated temperatures showed an association with preterm birth (1.02; 95% CI, 1.00-1.05).
…Read more: Same link as above
It is difficult to believe that people whose recent ancestors mostly came from Northern Europe are more able to tolerate heat than people whose ancestors mostly came from Africa. But these are peer reviewed studies.