Figure 1.

Estimated adjusted odds ratios (ORs) and 95% confidence intervals (CIs) between selected congenital heart defects and categories of nitrogen dioxide (NO₂) exposure and dietary intake of methionine, National Birth Defects Prevention Study, United States, 1997–2006. For perimembranous ventricular septal defect (A), pulmonary valve stenosis (B), and coarctation of the aorta (C). Reference group for all comparisons is NO₂ exposure less than the 10th centile and methionine intake at or greater than the 25th centile (high nutrient). The models adjusted for maternal race/ethnicity, age, education, household income, tobacco and alcohol use during pregnancy, use of folic-acid supplements 1 month prior to conception, and site-specific ratio of septal cases to total congenital heart defect cases. Filled circles correspond to ORs calculated for populations with methionine intake greater than the 25th centile, and filled squares correspond to ORs calculated for populations with methionine intake less than the 25th centile. “//” indicates truncation of the confidence interval.