University of Oulu

Nazeeba Siddika, Aino K. Rantala, Harri Antikainen, Hamudat Balogun, A. Kofi Amegah, Niilo R.I. Ryti, Jaakko Kukkonen, Mikhail Sofiev, Maritta S. Jaakkola, Jouni J.K. Jaakkola, Synergistic effects of prenatal exposure to fine particulate matter (PM2.5) and ozone (O3) on the risk of preterm birth: A population-based cohort study, Environmental Research, Volume 176, 2019, 108549, ISSN 0013-9351,

Synergistic effects of prenatal exposure to fine particulate matter (PM₂.₅) and ozone (O₃) on the risk of preterm birth : a population-based cohort study

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Author: Siddika, Nazeeba1,2; Rantala, Aino K.1,2; Antikainen, Harri3;
Organizations: 1Center for Environmental and Respiratory Health Research, Faculty of Medicine, P.O. Box 5000, FI-90014, University of Oulu, Oulu, Finland
2Medical Research Center Oulu, Oulu University Hospital, P.O. Box 8000, FI-90014, University of Oulu, Oulu, Finland
3Geography Research Unit, P.O. Box 3000, 90014, University of Oulu, Oulu, Finland
4Public Health Research Group, Department of Biomedical Sciences, University Post Office, University of Cape Coast, Cape Coast, Ghana
5Finnish Meteorological Institute, P.O. Box 503, FI-00101, Helsinki, Finland
Format: article
Version: accepted version
Access: open
Online Access: PDF Full Text (PDF, 0.4 MB)
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Language: English
Published: Elsevier, 2019
Publish Date: 2021-06-19


Background: There is some evidence that prenatal exposure to low-level air pollution increases the risk of preterm birth (PTB), but little is known about synergistic effects of different pollutants.

Objectives: We assessed the independent and joint effects of prenatal exposure to air pollution during the entire duration of pregnancy.

Methods: The study population consisted of the 2568 members of the Espoo Cohort Study, born between 1984 and 1990, and living in the City of Espoo, Finland. We assessed individual-level prenatal exposure to ambient air pollutants of interest at all the residential addresses from conception to birth. The pollutant concentrations were estimated both by using regional-to-city-scale dispersion modelling and land-use regression–based method. We applied Poisson regression analysis to estimate the adjusted risk ratios (RRs) with their 95% confidence intervals (CI) by comparing the risk of PTB among babies with the highest quartile (Q₄) of exposure during the entire duration of pregnancy with those with the lower exposure quartiles (Q₁-Q₃). We adjusted for season of birth, maternal age, sex of the baby, family’s socioeconomic status, maternal smoking during pregnancy, maternal exposure to environmental tobacco smoke during pregnancy, single parenthood, and exposure to other air pollutants (only in multi-pollutant models) in the analysis.

Results: In a multi-pollutant model estimating the effects of exposure during entire pregnancy, the adjusted RR was 1.37 (95% CI: 0.85, 2.23) for PM₂.₅ and 1.64 (95% CI: 1.15, 2.35) for O₃. The joint effect of PM₂.₅ and O₃ was substantially higher, an adjusted RR of 3.63 (95% CI: 2.16, 6.10), than what would have been expected from their independent effects (0.99 for PM₂.₅ and 1.34 for O₃). The relative risk due to interaction (RERI) was 2.30 (95% CI: 0.95, 4.57).

Discussion: Our results strengthen the evidence that exposure to fairly low-level air pollution during pregnancy increases the risk of PTB. We provide novel observations indicating that individual air pollutants such as PM₂.₅ and O₃ may act synergistically potentiating each other’s adverse effects.

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Series: Environmental research
ISSN: 0013-9351
ISSN-E: 1096-0953
ISSN-L: 0013-9351
Volume: 176
Article number: 108549
DOI: 10.1016/j.envres.2019.108549
Type of Publication: A1 Journal article – refereed
Field of Science: 3142 Public health care science, environmental and occupational health
Funding: This study was supported by the Academy of Finland [grant numbers 266314, 267675, 267995 (APTA Consortium) and 31071 and 31072 (GLORIA Consortium)], The Research Foundation of the Pulmonary Diseases and Nordforsk [grant number 75007 (NordicWelfAir)]. N.S. received PhD scholarships from the Health and Biosciences Doctoral Programme (HBS_DP) and the Oulu University Scholarship Foundation.
Academy of Finland Grant Number: 266314
Detailed Information: 266314 (Academy of Finland Funding decision)
267675 (Academy of Finland Funding decision)
267995 (Academy of Finland Funding decision)
Copyright information: © 2019 Elsevier Inc. All rights reserved. This manuscript version is made available under the CC-BY-NC-ND 4.0 license