Stingone JA, et al. – The goal of this current investigation was to explore the links between maternal exposure to nitrogen dioxide (NO2), dietary intake of methyl nutrients, and the odds of congenital heart defects in offspring, using data from the National Birth Defects Prevention Study (United States, 1997–2006). Findings offered modest evidence of interaction between nutrition and NO2 exposure during pregnancy.

Methods

• Researchers assessed associations between maternal exposure to nitrogen dioxide (NO2), dietary intake of methyl nutrients, and the odds of congenital heart defects in offspring, using data from the National Birth Defects Prevention Study (United States, 1997–2006).
• NO2 concentrations, a marker of traffic-related air pollution, averaged across postconception weeks 2–8, were assigned to 6,160 nondiabetic mothers of cases and controls using inverse distance-squared weighting of air monitors within 50 km of maternal residences.
• Using a food frequency questionnaire, consumption of choline, folate, methionine, and vitamins B6 and B12 were assessed.
• Furthermore, hierarchical regression models, which accounted for similarities across defects, were constructed, and relative excess risks due to interaction were calculated.  

Results

• Findings demonstrated that relative to women with the lowest NO2 exposure and high methionine intake, women with the highest NO2 exposure and lowest methionine intake had the greatest odds of offspring with a perimembranous ventricular septal defect (odds ratio = 3.23, 95% confidence interval: 1.74, 6.01; relative excess risk due to interaction = 2.15, 95% confidence interval: 0.39, 3.92).
• Researchers did not observe considerable departure from additivity for other defects.