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
Menstrual cycle continue to secrete progesterone to maintain the new pregnancy. Most pregnancy tests look for the presence of hCG. The uterine cycle has three phases: menses, proliferative, secretory. Menstruation (also called menstrual bleeding, menses, catamenia or a period) is the first phase of the uterine cycle. The flow of menses normally serves as a sign that a woman has not become pregnant. (However, this cannot be taken as certainty, as a number of factors can cause bleeding during pregnancy; some factors are specific to early pregnancy, and some can cause heavy flow.) "Eumenorrhea" denotes normal, regular menstruation that lasts for a