Increased tissue concentrations of arachidonic acid in umbilical artery and placenta in fetal growth retardation

Objective. To compare the fatty acid phospholipid composition of the umbili cal artery and the placenta in cases of fetal growth retardation (FGR) and of normal growth, as well as in symmetric and asymmetric FGR. Design. Case-control study. Setting. University hospital. Population. Thirty-nine FGR cases (12 asymmetric, 27 symmetric) and 78 case s with normal growth. Main outcome measures. Thin layer gas-liquid capillary chromatography of ph ospholipid fatty acids in umbilical artery and placental cotyledons. Newbor ns were classified as FGR if their weight was under the 10th percentile for our center. FGR was defined as symmetric if the ponderal index was >2.32, and as asymmetric if it was <2.32. Results. In FGR, arachidonic acid was significantly increased both in place nta (24.05% +/- 2.78 vs 22.46% +/- 2.93) and in umbilical artery (16.76% +/ - 2.40 vs 15.58% +/- 3.67). Indeed this increase was significantly higher i n asymmetric than in symmetric FGR (25.70 +/- 2.32 vs 23.32 +/- 2.68 in pla centa and 18.06 +/- 1.46 vs 16.14 +/- 2.53 in umbilical artery). On the oth er hand, in the placenta there were a number of differences in the metaboli c ratios analyzed when comparing symmetric and asymmetric FGR, indicating a lower DHA availability and a higher n-6 fatty acid elongation and desatura tion in asymmetric FGR. Conclusion. FGR is characterized by an increase in arachidonic acid both in the placenta and umbilical artery phospolipids, probably reflecting a diff erent mobilization from tissue stores. It is speculated that the different arterial composition could be partially responsible for the increased cardi ovascular risk of FGR in adulthood. On the other hand the metabolic status of the placenta concerning polyunsaturated fatty acids was very different i n symmetric and asymmetric FGR, suggesting a different pathogenesis.