The physiology of decidual prolactin and other decidual protein hormones.

Human decidual tissue, the specialized endometrium of the luteal phase of the menstrual cycle and pregnancy, synthesizes and releases prolactin, relaxin, renin, and at least three insulinlike growth factor (IGF)-binding proteins. Although the physiologic roles of these decidual protein hormones during pregnancy are unclear, numerous studies suggest that the hormones may act locally to affect the function of the placenta, decidua, and fetal membranes. In addition, the synthesis and release of these hormones appear to be regulated locally by factors produced by the placenta, decidua, and fetal membranes.