Figure 2.

Relative excess risk due to interaction (RERI) between maternal nitrogen dioxide (NO₂) exposure and methyl nutrient intake, National Birth Defects Prevention Study, United States, 1997–2006. For choline (A), methionine (B), dietary folate equivalents (C), vitamin B₆ (D), and vitamin B₁₂ (E). RERIs were calculated by comparing odds ratios of women with NO₂ exposure greater than or equal to the 90th centile and nutrient intake less than the 25th centile, women with NO₂ exposure greater than or equal to the 90th centile and nutrient intake greater than or equal to the 25th centile, and women with NO₂ exposure less than the 10th centile and nutrient intake greater than or equal to the 25th centile (referent: women with NO₂ exposure less than the 10th centile and nutrient intake greater than or equal to the 25th centile of nutrient intake). Confidence intervals (CIs) were calculated based on Wald-type statistics, as proposed by Hosmer and Lemeshow (42). ASD, atrial septal defect; AVSD, atrioventricular septal defect; CHD, congenital heart defect; COA, coarctation of the aorta; dTGA, dextro-transposition of the great arteries; HLHS, hypoplastic left heart syndrome; other cono, other conotruncal defects; PVS, pulmonary valve stenosis; TAPVR, total anomalous pulmonary venous return; TOF, tetralogy of Fallot; VSD_pm, perimembranous ventricular septal defect. “//” indicates truncation of the confidence interval.