Progesterone for Endometrial Support
After ovulation, the ovaries produce progesterone. Progesterone is a hormone that prepares the endometrium (the uterine lining) for the fertilized egg as it arrives from the fallopian tube. If the ovary fails to produce enough progesterone, infertility or early pregnancy loss may result. This condition is known as luteal phase defect. There are two possible treatments for luteal phase defect - clomiphene citrate (or gonadotropins) and progesterone.
Progesterone may be administered by daily injection, vaginal suppositories, or in pill form. It is very important to begin treatment at the right time. If progesterone treatment is started prior to ovulation it may actually interfere with the chance for conception. Low levels of progesterone can cause early pregnancy loss during the first 10 weeks. After 10 weeks the placenta takes over progesterone production.
The only recognized risk of this form of treatment is a theoretical one. Other forms of progesterone have been associated with congenital anomalies of babies exposed to the drug during the first 10 weeks of pregnancy. These "other forms" are different from the progesterone prescribed for infertility treatment. There is no clear evidence that the progesterone used for infertility treatment causes congenital anomalies in offspring. We acknowledge a theoretical risk of major organ anomalies with this form of therapy. Progesterone has been used to support pregnancies for decades and is a common therapy.