Adverse birth outcomes in Victoria, Australia in association with maternal exposure to low levels of ambient air pollution

Shannon Melody; Karen Wills; Luke D Knibbs; Jane Ford; Alison Venn; Fay Johnston

doi:10.1016/j.envres.2020.109784

Adverse birth outcomes in Victoria, Australia in association with maternal exposure to low levels of ambient air pollution

Environ Res. 2020 Sep:188:109784. doi: 10.1016/j.envres.2020.109784. Epub 2020 Jun 13.

Authors

Shannon Melody¹, Karen Wills², Luke D Knibbs³, Jane Ford⁴, Alison Venn², Fay Johnston²

Affiliations

¹ Menzies Institute for Medical Research, University of Tasmania, Tasmania, Australia. Electronic address: shannon.melody@utas.edu.au.
² Menzies Institute for Medical Research, University of Tasmania, Tasmania, Australia.
³ School of Public Health, The University of Queensland, Herston, Queensland, Australia.
⁴ Clinical and Population Perinatal Health Research, Kolling Institute, Northern Sydney Local Health District, Australia.

PMID: 32574853
DOI: 10.1016/j.envres.2020.109784

Abstract

Background: The relationship between maternal exposure to air pollution and birth outcomes is not well characterised where ambient air pollution is relatively low.

Objectives: We aimed to explore the association between maternal exposure to ambient nitrogen dioxide (NO₂) and fine particulate matter (PM_2.5) and a range of birth outcomes in Victoria, Australia. Secondary aims were to explore whether obstetric conditions, such as gestational diabetes mellitus (GDM) and hypertensive disorders of pregnancy, were effect modifiers in observed relationships.

Methods: We included all singleton births occurring in Victoria, Australia from 1^st March 2012 to 31^st December 2015 using routinely collected government data. Outcomes included birth weight, small for gestational age (SGA), term low birth weight (tLBW), large for gestational age (LGA), and spontaneous preterm birth (sPTB). We estimated exposure to annual ambient NO₂ and PM_2.5 concentrations, assigned to maternal residence at time of birth. Confounders included maternal, meteorological and temporal variables. Multivariable linear regression and log-binomial regression were used for continuous and dichotomous outcomes, respectively.

Results: There were 285,594 births during the study period. Average NO₂ exposure was 6.0 parts per billion (ppb, median 5.6; interquartile range (IQR) 3.9) and PM_2.5 was 6.9 μg/m³ (median 7.1, IQR 1.3). IQR increases in ambient NO₂ and PM_2.5 were associated with fetal growth restriction, including decrements in birth weight (NO₂ β -22.8 g; 95%CI -26.0, -19.7; PM_2.5 β -14.8 g; 95%CI -17.4, -12.2) and increased risk of SGA (NO₂ RR 1.08; 95%CI 1.06, 1.10; PM_2.5 RR 1.05; 95%CI 1.04, 1.07) and tLBW (NO₂ RR 1.06; 95%CI 1.01, 1.10; PM_2.5 RR 1.04; 95%CI 1.03, 1.08). Women with GDM and hypertensive disorders of pregnancy had greater decrements in birth weight in association with pollutant exposure.

Discussion: In this exploratory study using an annual metric of exposure, maternal exposure to low-level ambient air pollution was associated with fetal growth restriction, which carries substantial public health implications.

Keywords: Ambient air pollution; Birth weight; Fetal growth restriction; Preterm birth; Public health policy.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Air Pollutants* / analysis
Air Pollutants* / toxicity
Air Pollution* / adverse effects
Air Pollution* / analysis
Female
Humans
Infant, Newborn
Maternal Exposure / adverse effects
Particulate Matter / analysis
Particulate Matter / toxicity
Pregnancy
Premature Birth* / chemically induced
Premature Birth* / epidemiology
Victoria / epidemiology

Substances

Air Pollutants
Particulate Matter