Lower rate of selected congenital heart defects with better maternal diet quality: a population-based study

ObjectiveTo evaluate whether better diet quality in mothers is associated with lower risk for major non-syndromic congenital heart defects in their children.DesignMulticentre population-based case–control study, the National Birth Defects Prevention Study.SettingTen sites in the USA.ParticipantsMothers of babies with major non-syndromic congenital heart defects (n=9885) and mothers with unaffected babies (n=9468) with estimated date of delivery from 1997 to 2009.Main outcome measuresAdjusted ORs for specific major congenital heart defects by quartiles of maternal diet quality in the year before pregnancy, assessed by the Diet Quality Index for pregnancy (DQI-P) and the Mediterranean Diet Score. Quartile 1 (Q1) reflecting the worst diet quality and Q4 the best diet quality.ResultsBetter diet quality was associated with reduced risk for some conotruncal and atrial septal heart defects. For DQI-P, estimated risks reductions (Q4 vs Q1) for conotruncal defects were 37% for tetralogy of Fallot (OR 0.63, 95% CI 0.49 to 0.80) and 24% overall (OR 0.76, 95% CI 0.64 to 0.91); and for septal defects, 23% for atrial septal defects (OR 0.77, 95% CI 0.63 to 0.94) and 14% overall (OR 0.86, 95% CI 0.75 to 1.00). Risk reductions were weaker or minimal for most other major congenital heart defects.ConclusionsBetter diet quality is associated with a reduced occurrence of some conotruncal and septal heart defects. This finding suggests that a reduction in certain cardiac malformations may be an additional benefit of improved maternal diet quality, reinforcing current preconception care recommendations.