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Pollution exposure during pregnancy increases risk for high BP in childhood
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Children whose mothers were exposed to an ambient particulate matter concentration less than 2.5 µm during the third trimester had elevated BP at age 3 to 9 years, according to a study published in Hypertension.
“Ours is one of the first studies to show breathing polluted air during pregnancy may have a direct negative influence on the cardiovascular health of the offspring during
childhood,” Noel T. Mueller, PhD, MPH, assistant professor of epidemiology at the Johns Hopkins University Bloomberg School of Public Health, said in a press release. “High blood pressure during childhood often leads to high blood pressure in adulthood and hypertension is the leading cause of cardiovascular disease.”
Boston Birth Cohort
Mingyu Zhang, BSc, a biostatistician and research assistant at Johns Hopkins University, and colleagues analyzed data from 1,293 women and their children from the Boston Birth Cohort who gave birth from 1998 to 2012. Women who gave birth to newborns with major birth defects or had multiple gestation pregnancies were excluded from the study.
Exposure to pollution during pregnancy increases risk for high BP in childhood
Standardized questionnaires were completed to collect information on lifestyle, socioeconomic status, environmental factors, race, height, prepregnancy weight, alcohol consumption, smoking status and education.
The primary exposure of interest was the mother’s exposure to an ambient particulate matter concentration less than 2.5 µm during pregnancy, which was analyzed in each trimester. Ambient particulate matter concentrations were determined by matching the mother’s address to the nearest U.S. Environmental Protection Agency’s air quality monitor.
The primary outcome of interest was child systolic BP at the last recorded well-child visit between age 3 and 9 years.
A sharp increase was seen in the risk for increased BP and systolic BP percentile when the third-trimester ambient particulate matter concentration less than 2.5 µm was greater than 13 µg/m3.
Increased systolic BP
When compared with the lowest tertile of ambient particulate matter concentration less than 2.5 µm, those in the highest tertile had a 1.61 times increased risk for child elevated BP (95% CI, 1.12-2.3) or a 4.85 percentile increase in child systolic BP (95% CI, 1.38-8.37).
Child systolic BP increased by a 3.49 percentile (95% CI, 0.71-6.26) and the risk for elevated BP increased by 1.47 times (95% CI, 1.17-1.85) with a 5-µg/m3 increment in ambient particulate matter concentration less than 2.5 µm during the third trimester.
“The observed association between maternal [particulate matter ] 2.5 and offspring [systolic] BP association seems to be partly mediated by the effects of [particulate matter ] 2.5 on fetal and childhood weight gain,” Zhang and colleagues wrote. “If further confirmed, our findings provide new insight into early life origins of high BP and opportunities for early screening and primary prevention of hypertension in childhood and beyond.”
In a related editorial, Diane R. Gold, MD, and Antonella Zanobetti, PhD, both from the department of environmental health at Harvard T.H. Chan School of Public Health, wrote: “Even in the context of controlled human exposure studies, the search for thresholds for pollution effects can be a problematic exercise, as pollution effects vary by the sensitivity and vulnerability of individuals and populations. The Clean Air Act mandates that standards be established on the basis of responses in the most sensitive populations. Studies of cardiovascular outcomes and overall mortality in adults have found no threshold for adverse effects of [particulate matter ] 2.5 exposure, supporting the need for continued regulation and for local policies to reduce exposure.” – by Darlene Dobkowski
Disclosures: The Boston Birth Cohort was supported in part by grants from the March of Dimes and the NIH. The follow-up study was supported in part by the NIH and Maternal and Child Health Bureau. The authors report no relevant financial disclosures. Gold and Zanobetti report that their institution has received grant funding from the NIH.
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