The Impact of Ambient Air Pollutants on Birth Outcomes Using ARMA Model: Yazd Mother and Birth Cohort Study

The present study examines the association between ambient air pollution and harmful consequences at birth in Yazd, Iran during 2017-2020.

This time series study by the autoregressive (AR) and moving average (MA) or ARMA model was conducted in Yazd, Iran. Birth information including fetal sex, birth weight, birth height, and head circumference as well as preterm birth (PTB) and abortion was collected from mother and birth cohort databases. Data on air pollutants concentrations in the corresponding gestational period were obtained from fixed air monitors of Yazd Municipal Environmental Monitoring Center. The time series model statistical test was performed to find the relation between ambient air pollution and harmful consequences at birth.

2131 singleton live births were monitored for 3 years. In ARMA models, the ratio of girl births to total births (Coef: 7.943, 95% CI: 2.797, 13.089), preterm delivery (Coef: 2.915, 95% CI: 0.224, 5.606), and spontaneous abortion (Coef: 44.751, 95% CI: 26.872, 62.629) was associated with NO2 exposure. Distributed mismatch models also suggested associations between the Air Quality Index (AQI) in pregnant women with a sex-premature birth relationship (Coef: 0.001, 95% CI: 0.000, 0.001).

Exposure to air pollution, even at low levels, may increase the risk of sex ratio in singletons, premature birth, and spontaneous abortion. However, the results of the present study could not definitively show the relationship between air quality and other birth problems. More research studies are required to investigate the present findings.