Short-term prenatal exposure to ambient air pollution and risk of preterm birth - A population-based cohort study in Finland

• Published in: Environmental research Vol. 184; p. 109290
• Main Authors: Siddika, Nazeeba, Rantala, Aino K., Antikainen, Harri, Balogun, Hamudat, Amegah, A. Kofi, Ryti, Niilo R.I., Kukkonen, Jaakko, Sofiev, Mikhail, Jaakkola, Maritta S., Jaakkola, Jouni J.K.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier Inc 01-05-2020
• Subjects: Air pollution; Fine particulates; Nitrogen dioxide; Prenatal exposure; Preterm birth; Air pollution; Fine particulates; Preterm birth; Nitrogen dioxide; Prenatal exposure
• ISSN: 0013-9351; 1096-0953
• DOI: 10.1016/j.envres.2020.109290

Previous studies have provided evidence that prenatal exposure to low-level air pollution increases the risk of preterm birth (PTB), but the findings of the effects of short-term exposure have been inconclusive. Moreover, there is little knowledge on potential synergistic effects of different combinations of air pollutants.
To assess independent and joint effects of prenatal exposure to air pollutants during the week prior to the delivery on the risk of PTB.
The study population included 2568 members of the Espoo Cohort Study, living in the City of Espoo, Finland, born between 1984 and 1990. We assessed individual-level prenatal exposure to ambient air pollutants of interest based on maternal residential addresses, while taking into account their residential mobility. We used both regional-to-city-scale dispersion modelling and land-use regression–based method to estimates the pollutant concentrations. We contrasted the risk of PTB in the highest quartile (Q4) of exposure to the lower exposure quartiles (Q1-Q3) during the specific periods of pregnancy. We applied Poisson regression analysis to estimate the adjusted risk ratios (RRs) with their 95% confidence intervals (CI), adjusting for season of birth, maternal age, sex of the baby, family's socioeconomic status, maternal smoking, and exposure to environmental tobacco smoke during pregnancy, single parenthood, and exposure to other air pollutants (this in multi-pollutant models).
The risk of PTB was related to exposures to PM2.5, PM10 and NO2 during the week prior to the delivery with adjusted RRs of 1.67 (95%CI: 1.14, 2.46), 1.60 (95% CI: 1.09, 2.34) and 1.65 (95% CI: 1.14, 2.37), from three-pollutant models respectively. There were no significant joint effects for these different air pollutants (during the week prior to the delivery).
Our results provide evidence that exposure to fairly low-level air pollution may trigger PTB, but synergistic effects of different pollutants are not likely.
•Low-level air pollution exposure in the week just before delivery triggers PTB.•No synergistic effect of short-term exposure to air pollutants on the risk of PTB.•Seasons modify the effects of air pollutants on the risk of PTB.