Fetuses with intrauterine growth restriction (IUGR) are at increased risk of death and disease during neonatal, pediatric, and adult life. Postnatal deficits in essential fatty acids have been associated with the neural and vascular complications of premature neonates. We studied whether fetal-maternal fatty acid relationships are already impaired in utero in IUGR fetuses. Fetal (F) and maternal (M) fatty acid profiles were determined in utero in 11 normal [appropriate for gestational age (AGA)] and in 10 IUGR fetuses by fetal blood sampling (FBS) between 19 and 39 wk. Total plasma fatty acid concentrations were significantly higher in M than in F of both AGA (M: 2.03±0.53 mg/mL; F: 0.64±0.29 mg/mL; p< 0.001) and IUGR (M: 2.16±0.59 mg/mL; F: 0.73±0.17 mg/mL; p< 0.001). The F/M ratio was significantly higher for linoleic acid (AGA: 0.36±0.09; IUGR: 0.52±0.12; p< 0.01) and significantly lower for the long-chain polyunsaturated fatty acid docosahexaenoic acid (AGA: 1.94±0.32; IUGR: 1.25±0.19; p< 0.05) and arachidonic acid (AGA: 2.35±0.35%; IUGR: 2.04±0.3%; p< 0.05) in IUGR compared with AGA pregnancies. The differences observed in the relative amounts but not in total plasma concentrations of fatty acid fetal-maternal relationships in pregnancies associated with IUGR could be related to inadequate transplacental supply as well as to a fetal lack of the enzymes necessary for elaboration of these metabolically relevant conditionally essential fatty acids. These differences might have a role in determining the biochemical environment leading to the neural and vascular complications associated with IUGR.