(214) Newborn anthropometric alternations are associated with second-trimester exposure to low-levels air pollution

Objective: Accumulating evidence suggests that prenatal exposure to fine particulate matter (PM_2.5) is largely associated with adverse newborn's health outcomes. However, the relevant timing of exposures varies between studies and is yet unclear. Hence, we examined the association of several anthropometric measures with weekly PM_2.5 exposure throughout weeks of gestation.

Study Design: We recruited 1060 mother-infant pairs from two major hospitals in Israel. Data regarding daily PM_2.5 predictions were estimated on a 1_kmX1_km grid from satellite-based models, geocoded and overlaid geographically per each mother using ArcGIS. We conducted Linear Mixed-Effects Models to examine the association between birth weight, length, and head circumference and trimestral as well as weekly exposures to PM_2.5 from the last menstrual period to the day of delivery.

Results: Comparing to PM_2.5 exposure levels measured worldwide in a global analysis of air pollution conducted by the WHO, our study showed relatively moderate levels of daily mean PM2.5 concentrations (18.34 ±1.45 μg/m³). Prenatal exposure to PM_2.5 throughout the 2^nd and 3^rd trimesters (Figure 1) was significantly associated with decreased birthweight (β_trimester1= -0.021, CI: -0.046 to 0.002; β_trimester2= -0.035, CI: -0.059 to -0.012; β_trimester3 =-0.033, CI:-0.057 to -0.0095 respectively), with the most noticeable effect between the 15^th  to the 35^th gestational weeks. While head circumference was negatively associated with exposure to PM_2.5 in the first trimester (β= -0.019, CI:-0.035 to -0.0036 ), birth length was positively associated with exposures during the second trimester (β=0.026, CI:0.006-0.046).

Conclusion: Our findings suggest that PM_2.5  is significantly associated with a reduction in birth weight, with higher susceptibility between the 15^th to the 35^th gestational weeks. This critical window should be carefully assessed and could be the grounds for future clinical interventions. The trimestral associations of PM_2.5  with decreased head circumference and increased length could shed light on uncovered biological mechanisms that should be further studied.