Progesterone is initially produced by the corpus luteum, a small structure formed on the ovary when the egg is released from the ovarian follicle. After about twelve weeks, the placenta begins to produce progesterone. Progesterone is vital to pregnancy support because it causes increased vascularization (greater blood flow) and thickening of the endometrium, which is the inner layer of the uterus. If pregnancy does not occur, progesterone levels fall triggering menstruation. Menstruation is essentially "shedding" of the endometrial lining of the uterus. These processes increase the ability of the endometrium to provide vital nutrients to the developing embryo.
Progesterone is responsible for the temperature rise that is measured by the basal body temperature chart. Progesterone is sometimes used to treat a "luteal phase defect". The luteal phase is the period between ovulation and menses. Insufficient production of progesterone by the corpus luteum might not provide adequate stimulation of the endometrium to support a pregnancy. An endometrial biopsy is often taken to document a luteal phase defect.
Progesterone is used in in vitro fertilization cycles to insure adequate development of the endometrium. The injectable form of progesterone(Gestone) provides the most predictable blood levels and is often used in IVF. It is administered by intramuscular injection and is painful. Some clinics are now using a gel form (Crinone) which is administered intravaginally or specially compounded suppositories may be prescribed.
In some women the ovaries do not make enough progesterone or the lining of the uterus does not respond well to normal amounts of progesterone. If this happens the lining of the uterus is not able to thicken or prepare for implantation of the fertilized egg. This may result in the failure of the fertilized egg to implant and pregnancy does not occur. There are many reasons why the ovaries might not produce enough progesterone. The different causes may be ovulation problems, endometriosis, fertility drugs, or "older eggs".
Progesterone supplementation is a medication that is taken after ovulation and it corrects the low progesterone hormone imbalance. The lining of the uterus responds to the progesterone medication, it thickens and prepares for the implantation and support of a pregnancy. A woman will continue to use progesterone until the placenta has developed and is able to support the pregnancy. (11-13 weeks after conception).
Progesterone supplementation can be given in the form of vaginal suppositories, injections (shots) or by mouth. The progesterone is usually started four days after you have had the shot that causes ovulation to occur (hCG or Profasi). You will continue the progesterone until you have had a negative pregnancy test or a normal menstrual period. If you conceive and are pregnant you will continue the medication for several weeks; the doctor will tell you when it is time to stop. Progesterone supplementation has few side effects. These may include breast tenderness, nausea, fatigue, or a 2-3 day delay in the start of your period.
The medication may be packaged with a patient information insert. The purpose of this insert is to provide information about progesterone to all patients taking it. The information in the insert pertains to all progesterone medication, both natural and synthetic. There is an increased risk of birth defects to babies exposed during pregnancy to synthetic progesterone. However, the progesterone supplementation prescribed by the physician is in a natural form and this does not increase the risks of birth defects. Please talk with your physician if you have any concerns.
Progesterone Suppositories are inserted into your vagina and are then absorbed by the body. You may notice some leakage of the medicine from your vagina when you are up and moving around. Do not worry about this because the medication is still being absorbed. You may want to wear a panty liner to protect your clothing. There are no activity restrictions while using the suppositories, including sex. It probably would be more comfortable to wait until after intercourse before inserting the suppository. Occasionally the leakage of the medicine can be irritating to the skin around your vagina; contact your physician if the vaginal irritation becomes too bothersome.Progesterone Oral Medication comes in several different forms that are taken by mouth. Progesterone Injections are "shots" that are injected into your muscle (usually the buttocks or thigh) and the progesterone is absorbed by your body. You may notice soreness or tenderness at the injection site while you are taking the progesterone shots. After an injection you may apply an ice-pack to the area for relief. Please contact your physician if the injections become too painful.
Progesterone has many other uses not related to infertility treatment some of which have dubious scientific support.A qualified physician should be personally consulted prior to the administration of any hormone product.