['The aim of this study was to investigate how maternal polyunsaturated fatty acid intake at different periods during pregnancy affects the composition of polyunsaturated fatty acids in mature human milk.', 'A prospective study was conducted involving 45 pregnant women, aged between 18 and 35 y, who had full-term pregnancies and practiced exclusive or predominant breast-feeding. Mature breast milk samples were collected after the 5th postpartum week by manual expression; fatty acid composition was determined by gas chromatography. Fatty acid intake during pregnancy and puerperium was estimated through multiple 24-h dietary recalls. Linear regression models, adjusted by postpartum body mass index and deattenuated, were used to determine associations between estimated fatty acids in maternal diet during each trimester of pregnancy and fatty acid content in mature human milk.', 'A positive association was identified between maternal intake of eicosapentaenoic acid (β, 1.873; 95% confidence interval [CI], 0.545, 3.203) and docosahexaenoic acid (β, 0.464; 95% CI, 0.212-0.714) during the third trimester of pregnancy, as well as the maternal dietary ω-3 to ω-6 ratio (β, 0.093; 95% CI, 0.016-0.170) during the second and third trimesters and postpartum period, with these fatty acids content in mature breast milk.'] Does dietary polyunsaturated fatty acid intake during late pregnancy affect fatty acid composition of mature breast milk?