Studying empirically derived dietary patterns is useful in understanding dietary 
practice. We classified women by their dietary patterns using latent class 
analysis of 66 foods and studied the association of these patterns with neural 
tube defects (NTDs) and congenital heart defects (CHDs) in the U.S. National 
Birth Defects Prevention Study (1997-2005). Logistic regression models used data 
from 1,047 with an NTD, 6,641 with a CHD, and 6,123 controls that were adjusted 
for maternal characteristics and tested the effect modification of multivitamin 
supplement use. Four latent dietary patterns were identified: prudent, Western, 
low-calorie Western, and Mexican. Among participants who did not use 
supplements, those in the Mexican, Western, and low-calorie Western classes were 
significantly more likely (odds ratios of 1.6, 1.5, and 1.4, respectively) to 
have offspring born with NTDs than were those in the prudent class after 
adjustment of for dietary folic acid intake. In contrast, among supplement 
users, there was no difference in the incidence of NTDs between classes. 
Associations between dietary class and CHD subgroups were not modified by 
supplement use except for tetralogy of Fallot; among supplement users, those in 
the Western class were twice as likely (95% confidence interval: 1.4, 2.8) as 
the prudent class to have offspring with tetralogy of Fallot. Women who adhered 
to a Western diet were 1.2 (95% confidence interval: 1.03, 1.35) times more 
likely to have an infant with septal heart defect than were women who adhered to 
a prudent diet. A prudent dietary pattern, even with folate fortification, may 
decrease the risk of NTDs and some heart defects.