Article by Neal Rouzier, M.D. and Allen Lawrence, M.D.

The only time I felt normal was when I was pregnant. Otherwise, I was miserable one week out of every month. Now I feel great on progesterone — no more PMS, headaches, bloating or cramps. Finally I’m back to normal. Melanie D., Age 53.

Progesterone is a female hormone created by the ovaries in response to ovulation. Progesterone acts to prepare the lining of the uterus for pregnancy. If pregnancy does not occur, progesterone will stop being manufactured.

Production of Progesterone

Each month, starting with menarche, the onset of menstruation, a series of hormones are created in each woman that offers her the opportunity to become pregnant. This process starts deep within the Pituitary Gland, specifically in an area called the Hypothalamus where the menstrual cycling mechanism first starts by triggering the production of Follicle Stimulating Hormone or FSH.

FSH is released into the blood and travels through the body until it reaches the ovaries. Here it stimulates at least one cell to begin a difficult journey to become an oocyte or egg cell. As this future egg develops, the cells around it form a cyst or fluid filled structure to both protect and nourish it. The journey from a single cell to its completion as a full-blown egg cell takes around14 days. Some approximately two weeks prior to the next menstrual period ovulation occurs. The ovulation process is dramatic as the single egg cell reaches maturation, and explodes out of its protective encasement and out and away from the ovary to begin its long and dangerous journey first toward a Fallopian Tubes then up the Fallopian Tube to enjoin itself with a sperm cell, in a process called Fertilization. This of course, can only happen, if a sperm cell is available. If it is, from this union a new life, a fetus, may ultimately form if all other variables are right.

Preparing for Pregnancy

While all of this is going on, the hypothalamus produces a hormone called Leutinizing Hormone (LH) a bit over one week into the development of the new egg. The role of LH is to stimulate the development of the egg and the cystic structure it is encased in, the Corpus Luteum Cyst. With the release of LH and its affect on the ovaries and the corpus luteum cyst, progesterone production is also stimulated. Progesterone has a number of roles the most prominent is to prepare the lining of the uterus (the Endometrium) for the implantation of the fertilized egg and to assist the early growth of the fetus.

If pregnancy occurs, progesterone will be produced well into the first trimester, if fertilization or implantation does not occur, progesterone production will cease a few days prior to the onset of menstruation. In fact, it is the reduction in progesterone and decrease in estrogen production that may well trigger the onset of menstruation, the cleansing of the uterus which then sets the stage for this process to repeat itself over and over again for years or until pregnancy occurs.

The Reproductive Years

Progesterone is generally considered a pro-gestational or pregnancy hormone. It is absolutely necessary for the initiation and maintenance of pregnancy. Without progesterone women cannot prepare their uterus and make it ready for pregnancy. Without progesterone they could not sustain a pregnancy. Miscarriages would occur and the woman who does not make progesterone would become infertile, even if everything else was working correctly.

During the reproductive years, progesterone protects women against uterine cancer, breast cancer, osteoporosis and heart disease.

Menopause

As the reproductive era comes to an end, so does ovulation and with this, progesterone ceases to be a factor in the woman’s life. Without ovulation there is no more progesterone.

Progesterone is a female hormone of equal importance to estrogen as woman age. Unfortunately, it is commonly overlooked. Another role of progesterone in the healthy menstruating woman is to naturally balance estrogen. During the early years of the menopause the hypothalamus tries persistently to restart the reproductive process. It often produces large amounts of FSH and other hypothalamic hormones which in turn stimulate the ovaries to produce extreme amounts of estrogen. As estrogen levels raise and fall in the early years of menopause a series of symptoms anc changes occur. The symptoms are the symptoms associated with the menopause hot flashes, flushes, vasomotor instability, etc. The risks are over stimulation of the breasts with breast pain, breast cyst formation, even breast cancer. The uterus and its lining, the endometrium, may be repeatedly overstimulated and this is known to give rise to fibroid tumors and even endometrial cancer. As estrogen and progesterone levels fall during menopause osteoporosis, increased risk of heart disease and premature aging, all begin to become increasing problems for the menopause woman.

To go to the next article in this series, Progesterone -- Part 2, click here.