Progesterone is the hormone made by the ovary after ovulation and is responsible for maintaining the lining of the uterus. This is important because the fertilized egg must attach to the lining in order to grow. Progesterone also causes the small rise in body temperature that happens after ovulation. This is the rise in temperature that you measure if you are checking your basal body temperature.

Progesterone is measured by taking a blood test during the second part of your menstrual cycle, usually a week following ovulation (around day 21, day 22, or day 23). If ovulation has occurred, your provider will see a rise in your progesterone level. Please check with your provider to determine which day is best to have your blood test drawn.

A progesterone level should be around "10". If it is much lower and was taken at the right time of the menstrual cycle, this usually suggests a problem with ovulation. If the progesterone is around 10 or higher, this means that ovulation problems are not the reason for infertility.

If you are not ovulating correctly, your provider will evaluate a number of factors including weight, diet, blood tests, and other factors. Treatment is targeted to the problem. For instance, if you are overweight, weight loss usually causes ovulation to return, or even begin. Sometimes pills (like Clomiphene Citrate - Clomid®) or daily injections are used to help induce ovulation. Your progesterone levels will be checked while you are taking the medicines to see if the doses are right for you.