Abstract:
There is accumulating evidence that prenatal exposure to air pollution disturbs fetal growth
and development, but little is known about these effects in cold climates or their season-specific or
joint effects. Our objective was to assess independent and joint effects of prenatal exposure to specific
air pollutants on the risk of low birth weight (LBW). We utilized the 2568 children of the Espoo
Cohort Study, born between 1984 and 1990 and living in the City of Espoo. We conducted stratified
analyses for births during warm and cold seasons separately. We analyzed the effect estimates using
multi-pollutant Poisson regression models with risk ratio (RR) as the measure of effect. The risk of
LBW was related to exposure to CO (adjusted RR 1.44, 95% confidence interval [CI]: 1.04–2.00) and
exposure to O3 in the spring–summer season (1.82, 1.11–2.96). There was also evidence of synergistic
e ects between CO and O3 (relative risk due to interaction (RERI), all year 1.08, 95% CI: 0.27–4.94,
spring–summer 3.97, 2.17–25.85) and between PM2.5 and O3 (all year 0.72, 0.07–3.60, spring–summer
2.80, 1.36–19.88). We present new evidence of both independent and joint effects of prenatal exposure
to low levels of air pollution in a cold climate on the risk of LBW.
