['Arachidonic acid (AA) and docosahexaenoic acid (DHA) are important for growth and neural development. trans Fatty acids (TFAs) may inhibit desaturation of linoleic acid (LA) and alpha-linolenic acid (ALA) to AA and DHA, respectively. Conjugated linoleic acids (CLAs) also alter lipid metabolism and body fat.', 'We determined the associations of birth outcome with maternal and infant plasma concentrations of TFAs, CLAs, AA, and DHA.', 'In healthy women, we sampled maternal blood at 35 wk gestation (n = 58) and umbilical cord blood at birth (n = 70).', 'Mean (+/- SEM) TFA concentrations (% by wt) in infant plasma were as follows: triacylglycerol, 2.83 +/- 0.19 (range: 0.63-12.79); phospholipid, 0.67 +/- 0.03 (0.11-1.33); and cholesteryl ester, 2.04 +/- 0.01 (0.86-4.24). LA, AA, DHA, TFA, and CLA concentrations in infant phospholipids correlated with the same fatty acid in maternal plasma phospholipids (n = 44; P < 0.05). Infant plasma cholesteryl ester and triacylglycerol TFAs and cholesteryl ester CLAs (r = -0.33, -0.42, and -0.49, respectively) were significantly inversely related to length of gestation. Triacylglycerol and cholesteryl ester AA were positively related to length of gestation (r = 0.41 and 0.37, respectively) and birth weight (r = 0.27 and 0.23, respectively). Inverse correlations occurred between infant plasma TFA and DHA concentrations in triacylglycerols (r = -0.33) and between TFA and AA concentrations in cholesteryl esters (r = -0.23).'] Are infant plasma trans , n-6 , and n-3 fatty acids and conjugated linoleic acids related to maternal plasma fatty acids , length of gestation , and birth weight and length?