BACKGROUND:Inflammation during pregnancy may be a factor in the developmental programming of asthma and wheeze in childhood. OBJECTIVE:To examine associations of inflammatory potential of prenatal diet with respiratory outcomes in early childhood and midchildhood. METHODS:Among 1424 mother-child pairs in Project Viva, a prebirth cohort, we examined associations of Dietary Inflammatory Index (DII®) (first trimester, second trimester, and average of first and second trimesters) scores in relation to ever asthma and wheezing in the past year (early childhood and midchildhood); current asthma and lung function (midchildhood), and wheeze trajectory during 1 to 9 years. We used multivariable linear and logistic regression modeling, adjusting for relevant confounders. RESULTS:In a fully adjusted analysis, a more proinflammatory diet was associated with an early versus never wheeze trajectory (first- and second-trimester average fourth vs first quartile: odds ratio, 1.89; 95% CI, 1.14-3.13). A more proinflammatory diet during pregnancy also was associated with lower forced expiratory flow (forced expiratory flow at 25%-75%) in midchildhood (first- and second-trimester average fourth vs first quartile: β, -132 mL; 95% CI, -249 to -14). Results were evident for first-, but not second-, trimester DII and wheeze trajectory and midchildhood forced expiratory flow at 25% to 75%. Other child respiratory outcomes, including ever asthma, were not related to any DII measure during pregnancy. CONCLUSIONS:Proinflammatory diet during pregnancy is associated with wheeze trajectory during early childhood and decrements in small airways caliber in midchildhood, but not other respiratory outcomes in the offspring.