Prostaglandin biosynthesis stimulatory and inhibitory substances in human amniotic fluid during pregnancy and labor

Human amniotic fluid has been separated into two fractions; one fraction inhibits prostaglandin biosynthesis and the other fraction is stimulatory. The activity of the stimulatory fraction increased with increasing gestational age and was greater still during labor. The activity of the inhibitory fraction decreased with increasing gestational age and was smaller still during labor. We speculate that these changes may play a significant role in parturition.