Prolongation of rat gestation time by unsaturated fatty acids.

Arachidonic, linoleic, linolenic, and oleic acids, administered to Sprague-Dawley rats on Days 20 and 21 of gestation prolonged the gestation time; neither the duration parturition, parturitional bleeding, nor the perinatal mortality rate was affected. Since arachidonic acid is the obligatory precursor of prostaglandins E2 and F2 alpha, currently believed to be associated with the initiation of labor, and polyunsaturated fatty acids inhibit the cell-mediated immune response in vivo, the precise role of prostaglandins and their precursors in the initiation of parturition must be critically examined.