Traffic-related air pollution has been linked to multiple adverse pregnancy outcomes. However, few studies have examined pregnancy loss, targeting losses identified by hospital records, a large limitation as it does not capture events not reported to the medical system.
We used a novel variation of the time-series design to determine the association, and identify the critical window of vulnerability, between week-to-week traffic-related air pollution and conceptions resulting in live births, using nitrogen dioxide (NO2) as a traffic emissions tracer. We used information from all live births recorded at Beth Israel Deaconess Medical Center in Boston, MA (2000–2013) and all live births in Tel Aviv District, Israel (2010–2013).
In Boston (68,969 live births), the strongest association was during the 15th week of gestation; for every 10 ppb of NO2 increase during that week, we observed a lower rate of live births (rate ratio [RR] = 0.87; 95% confidence interval [CI], 0.78, 0.97), using live birth–identified conceptions to infer pregnancy losses. In the Tel Aviv District (95,053 live births), the strongest estimate was during the 16th gestational week gestation (RR = 0.82; 95% CI, 0.76, 0.90 per 10 ppb of NO2).
Using weekly conceptions ending in live birth rather than identified pregnancy losses, we comprehensively analyzed the relationship between air pollution and all pregnancy loss throughout gestation. The observed results, with remarkable similarity in two independent locations, suggest that higher traffic-related air pollution levels are associated with pregnancy loss, with strongest estimates between the 10th and 20th gestational weeks.
From the aDepartment of Environmental Health Sciences, Columbia University Mailman School of Public Health, New York, NY
bBraun School of Public Health and Community Medicine, The Hebrew University of Jerusalem Jerusalem, Israel
cDepartment of Statistics, Colorado State University Fort Collins, CO
dDepartment of Statistics, The Hebrew University of Jerusalem Jerusalem, Israel
eFaculty of Civil and Environmental Engineering, Technion, Israel Institute of Technology, Haifa, Israel
fDepartment of Obstetrics and Gynecology, Beth Israel Deaconess Medical Center, Harvard Medical School Boston, MA
gDepartment of Epidemiology, Harvard T.H. Chan School of Public Health Boston, MA
hDivision of Maternal-Fetal Medicine, Brigham & Women’s Hospital, Harvard Medical School Boston, MA
iBen-Gurion University of the Negev, Beer Sheva, Israel
jPublic Health Services, Ministry of Health, Jerusalem, Israel
kDepartment of Environmental Health, Harvard T.H. Chan School of Public Health Boston, MA.
Submitted April 9, 2018; accepted September 5, 2018.
This work grew out of work related to specific aims #1 & 2 of Grant R21 ES026900 to Dr. Weisskopf from NIEHS. This work was also supported by Grants T32 ES007069, P30 ES000002, and P30 ES009089 from NIEHS. This publication was partially made possible by USEPA Grant RD-835872. Its contents are solely the responsibility of the grantee and do not necessarily represent the official views of the USEPA. Further, USEPA does not endorse the purchase of any commercial products or services mentioned in the publication.
The authors report no conflicts of interest.
The authors Kioumourtzoglou and Raz contributed equally to this study.
All data used and computing code developed for the analyses described in this article can be available upon request, subject to the access requirements of the institutions that provided the data. Due to identifiability concerns, only weekly counts of live birth–identified conceptions can be available both for Tel Aviv District, Israel, and the Beth Israel Deaconess Medical Center in Boston, MA. For Tel Aviv District, weekly district-wide NO2 averages can also be available upon request. For Boston, all NO2 data were downloaded from the US Environmental Protection Agency’s Air Quality System (AQS) database (https://www.epa.gov/aqs). The weekly city-wide averages of NO2 that we used for our analyses can also be shared, however, to ensure full reproducibility.
Supplemental digital content is available through direct URL citations in the HTML and PDF versions of this article (www.epidem.com).
Correspondence: Marianthi-Anna Kioumourtzoglou, Department of Environmental Health Sciences, Columbia University Mailman School of Public Health, 722 West 168th Street, #1104B, New York, NY 10032. E-mail: mk3961@cumc.columbia.edu.
