County-level pesticide use and risk of shortened gestation and preterm birth

This study assesses the association between pesticide exposure in pregnancy, preterm birth (PTB) and shortened gestation.

Pregnancy information was abstracted from the Centers for Disease Control (CDC) Non-Public Use Natality Datasets 1990-2005. Pesticide use in maternal county of residence was calculated using California Pesticide Use Reporting (PUR) data 1990-2005. Counties were ranked by pesticide use, and birth months were sorted by peak (May-June) or nonpeak (other months) pesticide use. Multivariate logistical regression models were used.

Counties with higher pesticide use were associated with higher PTB (low 8.59 ± 0.11%, moderate 9.25 ± 0.07%, high 10.0 ± 0.06%, p's < 0.001) and shorter gestations (low 39.197 ± 0.014 weeks, moderate 39.126 ± 0.011 weeks, high 39.049 ± 0.011 weeks, p's < 0.001). Peak pesticide months were associated with higher PTB (10.01 ± 0.05% vs. 9.36 ± 0.05%, p < 0.001) and shorter gestations (39.069 ± 0.007 weeks vs. 39.122 ± 0.007 weeks, p < 0.001). The pesticide effect on shortened gestation and higher PTB was found in all racial groups. Pesticide use was highest for fungicides > insecticides > fumigants > herbicides > others. Each pesticide type was found to be associated with higher PTB and shorter gestation.

PTB and shortened gestation were significantly associated with pesticide use in maternal county of residence regardless of race, gestation at birth, and in most risk categories.