Endocrinology of reproduction half of pregnancy, progesterone and prolactin prepare the mammary glands for lactation. Estrogens and progesterone promote mammary epithelial cell proliferation resulting in the formation of the primary and secondary ductal structure. Progesterone induces formation of tertiary side-branches in the mammary glands during puberty and during the luteal phase of the menstrual cycle upon which lobuloalveolar structures form under the influence of prolactin. Prolactin stimulates lactogenesis. hCG appears to be soporific during pregnancy; levels of hCG correlate with sleep changes during pregnancy, and administration of hCG increases sleep in rats likely via neuronal LHCGR. Endocrinology of reproduction Hormonal regulation occurs at
Topical progesterone of tissue exposure to progesterone with this route of administration. These findings provide a possible explanation for how some studies found antiproliferative and atrophic changes in the endometrium with topical progesterone. However, elevated levels of progesterone in the endometrium with topical progesterone have not yet been demonstrated. Concern has been raised regarding topical progesterone in that the effects of such supraphysiological levels of progesterone in tissues are unknown and hence the potential for harmful effects has not been ruled out. Salivary monitoring of progesterone levels in women using topical progesterone and adjustment of dosage as necessary has been suggested as