Relative fatty acid composition of serum lecithin in the second half of the normal pregnancy.

Fasting vein blood samples from 21 apparently normal pregnant women were collected in 4-week intervals from the 24th week of gestation until delivery. The relative fatty acid composition of serum lecithin was analyzed by gas-liquid chromatography. Palmitic acid increased successively concomitant with a decrease in stearic acid which indicates that serum lecithin is predominantly synthesized along pathway I. Linoleic acid decreased successively parallel to an increased incorporation of longer polyunsaturated fatty acids and non-essential monoenoic (palmitoleic and oleic) acids. The increased incorporation of longer polyunsaturated fatty acids is suggested to be associated with the increased activity of the deacylation-reacylation cycle. The increase of nonessential monoenoic fatty acids is suggested to be associated with a reduced de novo incorporation of linoleic acid.