The fatty acid composition of plasma lipids was determined in 41 pairs of mothers and their term infants at time of birth (38-42 postmenstrual weeks) by high-resolution capillary gas-liquid chromatography, Linoleic and alpha-linolenic acids were found at smaller concentrations in cord than in maternal triglycerides, in contrast to strikingly higher proportions of their long-chain polyunsaturated metabolites (IC-PUFA), which indicates a preferential maternofetal transport for certain physiologically important LC-PUFA. While no significant gestational age-dependent changes occurred in maternal plasma triglycerides, the values for most of the fetal long-chain n-3 metabolites increased with the duration of gestation, possibly reflecting an increased transplacental fatty acid passage during late pregnancy or a maturation of desaturation in the fetal liver, Copyright (C) 2000 S. Karger AG, Basel.