Whether maternal macro-environmental chemical
fertilizer exposure has an association with the risk of
preterm birth remains unclear. This study aimed to investigate the association between maternal exposure to chemical
fertilizer during pregnancy and the risk of
preterm birth. A total of 13,861 births, including 402
preterm birth from 313 villages in Pingding County, Shanxi Province, China, were analyzed to explore spatial variations of
preterm birth risks at the village level. Spatial variations of
preterm birth were visualized and tested with Disease Mapping, Moran's I and G* Statistic. The spatial zero-inflated negative binomial model was used to evaluate the incidence rate ratio (
IRR) of
preterm birth in different chemical
fertilizer consumption levels at the village level. A population-based case-control study was conducted including 153
preterm births cases and 204 controls at the household level. The two-level logistic regression model was performed to estimate the association between risks of
preterm birth and maternal exposure to chemical
fertilizer after adjusting confounding factors. The findings indicated a remarkably clustering effect in relative risks of
preterm birth and identified a high-risk clustering region of
preterm birth from the south-central to the southwest and a low-risk clustering region in the northern Pingding county. The results of the spatial zero-inflated negative binomial model showed that the risk of
preterm birth in the villages with chemical
fertilizer consumption≥100 tons was 2.82 (95% CI: 1.50-5.57) times higher than those with <50 tons. Maternal exposure to chemical
fertilizer ≥100 tons at village level was associated with an increased risk of
preterm birth (aOR 2.14, 95%CI: 1.18-3.96), compared with exposure <50 tons after adjusting for confounding variables. The findings suggests that chemical
fertilizers deserve more attention as a potential risk factor of
preterm birth.