Background: Birth weight (BW) and preterm birth (PTB) increase the risk of impaired lung function. Decreasing the risk of low BW and PTB may improve respiratory health.

Aim: To investigate the association of maternal exposure to air pollution and greenness during pregnancy with BW and PTB.

Methods: We analysed data on 5434 children from 2742 mothers within the Respiratory Health in Northern Europe (RHINE) study. Exposure to greenness (Normalized Difference Vegetation Index, NDVI), modelled particulate matter (PM_2.5 and PM₁₀), nitrogen dioxide (NO₂), ozone (O₃), and black carbon (BC) were estimated for mothers based on residential address at each pregnancy. We used two-level (level 1: offspring; level 2: mother) linear and logistic regression models, while adjusting for centre, maternal age, education, smoking, body silhouette, and comorbidity.

Results: Median (interquartile range, IQR) NDVI_300m was 0.3(0.2-0.4), for pollutants in µg/m3 was 9.5(7.1-13.0), 16.4(11.1-21.3), 15.8(8.9-21.6), 49.5(45.2-54.0), and 0.6(0.4-0.8) for PM_2.5, PM₁₀, NO₂, O₃ and BC respectively. An IQR increase in NDVI_300m was associated with an increase in BW of 29g (95%CI: 13-44), 23% lower odds of low BW (<2500g) (OR=0.77, 95% CI:0.64-0.94), and 14% increased odds of high BW (>4000g) (OR=1.14, 95% CI:1.02-1.26). The association was consistent after adjusting for air pollutants’ exposures or using different NDVI buffers(100m and 500m). No association of greenness exposure with PTB were observed. Air pollution exposure was associated with neither BW nor PTB.

Conclusion: Maternal long-term exposure to greenness has a positive association with BW. Greenness could contribute to healthier pregnancies and improve lung health.