66,000 pregnant Norwegian women answered food frequency questionnaires and were subsequently classified into three dietary pattern groups: “prudent” (vegetables, fruits, oils, water as beverage, whole grain cereals, fiber-rich bread), “Western” (salty and sweet snacks, white bread, desserts, processed meat products) and “traditional” (potatoes, fish). They found that women following a “prudent” or “traditional” diet were at a lower risk of preterm delivery.
BMJ. 2014 Mar 4;348:g1446. (Englund-Ögge et al.)