Also called phosphatides, they are compounds of various phosphorous-containing lipids that are composed of a glycerol molecule bonded to two fatty acid molecules, and a phosphate group with a nitrogen-containing component. The phospholipids lecithins and sphingomyelin facilitate the maturation of the fetal lungs before birth. Those belonging to cell membranes form a two-molecule thick sheet with water-soluble and fat-soluble regions, the former shielding the latter on both sides, thus providing a stable structure that preserves the integrity of the membrane.
See Amniotic fluid, Lipids, Phosphate