Allergic diseases in children are increasing. While maternal diet quality in pregnancy may be protective, it is unclear which measure of maternal diet best predicts offspring diseases.

To examine the associations between multiple diet measures and allergy outcomes, and to compare the diagnostic accuracy of the measures for the prediction of allergy outcomes.

Maternal diet during pregnancy was measured using a validated instrument, and scored using five measures: the maternal diet index (MDI), healthy eating index (HEI), total diet diversity (TDD), healthy diet diversity (HDD), and unhealthy diet diversity (UDD). Unadjusted and adjusted logistic regression models assessed associations between maternal diet measures and offspring allergy outcomes up to age four. The diagnostic accuracy of the diet measures was compared.

There were significant associations between MDI (OR=0.78; 95% CI: 0.70, 0.87), HEI (OR=0.98; 95% CI: 0.97, 0.99), and HDD scores (OR=0.91; 95% CI: 0.85, 0.98) during pregnancy and the primary combined outcome “any allergy excluding wheeze” in children up to age four years. Neither maternal TDD (OR=0.99; 95% CI: 0.95, 1.03) nor UDD scores (OR=1.05; 95% CI: 0.98, 1.13) were associated with the “any allergy excluding wheeze” outcome. For all outcomes studied, except for food allergy, there was a significant difference in the diagnostic accuracy between the five measures of maternal diet. The AUC for MDI was highest for every disease outcome, although not always significantly higher.

Better quality and higher diversity of a woman’s diet during pregnancy, measured in various ways, is associated with offspring allergy outcomes, with healthy foods associated with decreased risk, and unhealthy foods associated with higher risk. The maternal diet index, which appropriately weighted both healthy and unhealthy foods, best predicted childhood allergic disease.