Effect of ambient air pollution on premature SGA in Changzhou city, 2013-2016: a retrospective study

Abstract

Background: Air pollution is becoming an increased burden to the world. Previous studies have confirmed its effects on adverse birth outcomes, but few associated with premature small for gestational age (SGA). We report a retrospective cohort study conducted in Changzhou city to evaluate the association between air pollutants (PM_2.5, SO₂ and NO₂) and premature SGA during pregnancy.

Methods: A total of 46,224 births were collected from January, 2013 to December, 2016, in Changzhou Maternity and Child Health Care Hospital, finally 2709 preterm births were admitted for study. Corresponding air monitoring data were collected from Changzhou Environmental Protection Agency. Generalized estimating equations were used to examine the association between these air pollutants and premature SGA controlling for individual covariates in single- and multi-pollutant models.

Results: We found that, in the third trimester, every 10 μg/m³ increments in PM_2.5 concentration were associated with premature SGA (OR = 1.18, 95% CI: 1.03-2.83; OR = 1.37, 95% CI: 1.03-3.58) in two- and three-pollutants models. In the whole gestation, a 10 μg/m³ increment in PM_2.5 concentration in two- and three-pollutant models were related to premature SGA (OR = 1.53, 95% CI: 1.38-2.47; OR = 1.73, 95% CI: 1.18-2.57). The OR (95% CI) of premature SGA were increasing across quintiles of PM_2.5, SO₂, NO₂ concentrations during the whole gestation period adjusting for confounders (P _{for trend} < 0.001).

Conclusions: These results indicated that pregnant women exposed to PM_2.5, combined with other pollutants in the third trimester have a higher risk to deliver premature SGA babies, providing further evidence linking PM_2.5 and pregnancy outcomes.

Keywords: Air pollution; Exposure windows; Premature SGA; Retrospective study.

Fig. 1

The median concentrations of air pollutants and incidences of premature SGA from 2013 to 2016. SGA: small for gestational age, PM2.5: particular matter 2.5, NO₂: nitrogen dioxide, SO₂: sulphur dioxide

Fig. 2

Location of monitoring sites and subjects. Six monitoring sites and 2709 pregnant women with premature births were marked by red pentagrams and black solid dots, respectively. The map was generated by the professional software (ARCGIS, version 10.3; ESRI, Redlands, CA, USA)

Fig. 3

Associations of air pollutants with SGA in three-pollutants model over the entire pregnancy period. These were estimated using generalized estimating equations adjusting for infant gender, maternal age and parity, year of birth, and season of birth in SGA models, and gestational age and meteorological information (mean temperature, relative humidity and air pressure) were also included. PM_2.5: particular matter, NO₂: nitrogen dioxide, SO₂: sulphur dioxide, SGA: small for gestation age

Fig. 4

Concentration-response relationships between air pollutants and SGA in three-pollutants model over the entire pregnancy period. These were estimated using restricted cubic spline regression model adjusting for infant gender, maternal age and parity, year of birth, season of birth and meteorological information (mean temperature, relative humidity and air pressure) in multi-pollutants models. PM_2.5: particular matter, NO₂: nitrogen dioxide, SO₂: sulphur dioxide, SGA: small for gestation age