Progesterone is an important female hormone; it plays a crucial role in embryo implantation and growth during the secretory phase of the menstrual cycle, which follows ovulation. After ovulation, the leftover remnant of the follicle that contained an egg, called the corpus luteum, produces progesterone. Artificial progesterone, called progestin, is part of birth control pills and hormone replacement medications. Laboratory-made natural progesterone supplements are often taken by women undergoing assisted reproductive technologies, such as in-vitro fertilization.
Uterine Lining
Progesterone of any type builds up the uterine lining and changes its composition so a developing embryo can implant. During the two weeks after ovulation, the corpus luteum produces progesterone. After two weeks, if no embryo implants, the corpus luteum begins to deteriorate and stops producing progesterone. Without progesterone, the uterine lining breaks down and another menstrual cycle starts. When women who take artificial progesterone stop taking the pill it brings on a withdrawal bleed similar to a regular menstrual period. If pregnancy occurs, human chorionic gonadotropin, which is produced by the placenta, signals the corpus luteum to keep producing progesterone. After several weeks, the placenta begins to produce progesterone of its own.
Uses
Women undergoing IVF often have higher than normal estrogen levels after taking fertility medications. Because estrogen and progesterone levels must be kept in balance, they often take natural progesterone supplements in the form of creams or pills until their pregnancy test. Taking progesterone does not affect the results of a pregnancy test, which tests levels of hCG. Women who don't ovulate regularly may take artificial progesterone to bring on a regular withdrawal bleed. A uterine lining that continually builds up without being shed increases the risk of developing uterine cancer. When used as birth control, progestins interfere with follicle development and normal uterine lining development.
Side Effects
Progesterone, either naturally produced or given in supplements, has a number of side effects. Bloating, fluid retention, fatigue, dizziness, headache, nervousness, weight gain and elevated blood pressure are common side effects of progesterone. More serious side effects include an increased risk of developing blood clots, depression, rash or liver problems.
Risks
Women trying to get pregnant should take only natural forms of progesterone. Artificial progestins such as medroxyprogesterone may double the risk of hypospadias, an abnormal placement of the opening at the tip of the penis in a male fetus, according to the makers of Provera. Mild virilization of female sex organs in a female fetus may also occur. Post-menopausal women should not take progesterone without discussing its use with their medical practitioners, since the effects on the heart and the risks of developing breast or uterine cancer are still under study, according to Drugs.com.
