PM2.5 and NO2 Exposure During Pregnancy and Measures of Fetal Size and Attained Size at Birth

Air pollution exposure during pregnancy has been associated with reduced fetal size and birth weight, but the sensitive exposure windows for these associations are not well established. We examined the association between gestational air pollution exposure and altered fetal size (femur length, biparietal diameter, head circumference, abdominal circumference, estimated fetal weight), measured in mid-pregnancy (week 20) and late-pregnancy (week 34), and attained size at birth (Z-scores of birth weight, length, and head circumference). Within the UPSIDE cohort study (N = 312 pregnant women) in Rochester, New York, we estimated residential, daily, ambient PM2.5 and NO2 concentrations using a spatial-temporal model. Distributed lag models estimated increases/decreases in each marker associated with interquartile range (IQR) increases in gestational week mean PM2.5 (3 µg/m3) and NO2 (9 ppb) concentrations, adjusting for child sex, maternal pre-pregnancy body mass index, race/ethnicity, and smoking during pregnancy. For birth measures, gestational age at birth was also included. Each IQR increase in NO2 in gestational weeks 18–33 was associated with decreased femur length at week 34 (-1.18 mm; 95