Maternal Serum Nitrate and Nitrite Associations With Birth Outcomes: A Case-Control Study

Nitrate and nitrite contamination of groundwater and surface water is a global public health concern, often linked to the increasing use of nitrogen-based fertilizers. In Jordan's Ghor region, where agriculture is intensive and fertilizer use is widespread, the issue is particularly relevant. This study aimed to investigate the relationship between serum nitrate and nitrite levels with low birth weight and preterm birth. A total of 659 participants were enrolled, comprising 452 controls (normal birth weight and full-term delivery) and 207 cases (low birth weight/preterm delivery). High maternal serum nitrite levels were significantly associated with increased odds of low birth weight delivery in both the unadjusted model (odds ratio [OR] = 1.43, 95% CI: 1.14-1.80, P = 0.002) and the a priori confounder set adjusted model (OR = 1.33, 95% CI: 1.02-1.74, P = 0.038). Nitrite levels were also significantly associated with the combined outcome of preterm and/or low birth weight delivery in the unadjusted model (OR = 1.26, 95% CI: 1.01-1.57, P = 0.036), and this association remained significant after a priori adjustment in a multiple-imputation sensitivity analysis (OR = 1.29, 95% CI: 1.03-1.63, P = 0.029). In conclusion, although metabolically interrelated, nitrite and nitrate levels in pregnant women may differentially impact pregnancy outcomes in the largely low income agricultural communities in the Ghor region in Jordan.