Objective To examine maternal dietary intake and preterm delivery.

Study Design Data included 5738 deliveries from the National Birth Defects Prevention Study. Odds ratios (ORs) reflected risks of delivery at <32, 32–34, or 35–36 versus ≥37 weeks for maternal intake in the lowest or highest quartile of nutrient intake compared with the middle two.

Results Among deliveries < 32 weeks, many ORs were ≥1.5 or ≤0.7, but few confidence intervals excluded one. ORs were ≥1.5 for lowest quartiles of protein, thiamin, riboflavin, choline, vitamin A, α-carotene, β-carotene, vitamin E, iron, copper, and zinc and for highest quartiles of carbohydrate, glycemic index, and Mediterranean Diet Score. ORs were ≤0.7 for lowest quartiles of glycemic index and betaine and for highest quartiles of protein, alanine, methionine, vitamin B₆, betaine, and calcium. Few ORs met these criteria for later preterm deliveries.

Conclusions Results suggested an association of nutrient intake with earlier preterm deliveries.