Maternal exposure to ambient fine particulate matter and fetal growth in Shanghai, China

Abstract

Background

Fetal growth restriction (FGR) is not only a major determinant of perinatal morbidity and mortality but also leads to adverse health effects in later life. Over the past decade, numerous studies have indicated that maternal exposure to ambient air pollution has been a risk factor for abnormal fetal growth in developed countries where PM _2.5 levels are relatively low. However, studies in highly polluted regions, such as China, and studies that rely on assessments in utero are scarce.

Methods

A total of 7965 women were selected from 11,441 women from the Shanghai Maternity and Infant Living Environment (SMILE) cohort who were pregnant between January 1, 2014, and April 30, 2015. From January 1, 2014, to April 30, 2015, weekly average PM _2.5 values from 53 monitors were calculated and the inverse distance weighted (IDW) method was used to create a Shanghai pollution surface map according to the participants residential addresses. Individual exposure was the average PM _2.5 value of every gestational week between the first gestational week and one week before the ultrasound measurement date (the range of measurements per participant was 1 to 10). Repeated fetal ultrasound measurements during gestational weeks 14~40 were selected. The estimated fetal weight (EFW) was calculated by biparietal diameter (BPD), abdominal circumference (AC), and femur length (FL) formulas. In total, 29,926 ultrasound measurements were analysed. Demographic variables, other pollutants (SO ₂, NO ₂, PM ₁₀ and O ₃) and relative humidity and temperature were controlled for potential confounding through generalized estimating equations (GEE).

Results

The full model showed that with each 10 μg/m ³ increase in PM _2.5 exposure, the means (mm) of AC, BPD, FL decreased by 5.48 (− 9.06, − 1.91), 5.57 (− 6.66, − 4.47), and 5.47 (− 6.39, − 4.55), respectively; the mean EFW decreased by 14.49 (− 16.05, − 13.49) grams by Hadlock’s third formula and 13.56 (− 14.71, − 12.50) grams by Shepard’s formula with each 10 μg/m ³ increase in PM _2.5 exposure.

Conclusions

A negative correlation existed between maternal PM _2.5 exposure during pregnancy and fetal growth indicators, which may increase the risk of fetal growth restriction.

Electronic supplementary material

The online version of this article (10.1186/s12940-019-0485-3) contains supplementary material, which is available to authorized users.