Progesterone is a female hormone produced by the ovaries during ovulation. A progesterone test measures the amount of the hormone progesterone in a blood sample and to helps determine the cause of infertility in women. It is used to determine whether or not a woman has ovulated, when ovulation occurred, or to monitor the success of induced ovulation. An imbalance between progesterone and estrogen is linked to weight gain, insomnia, anxiety, depression, migraine, cancer, uterine fibroids, ovarian cysts, and osteoporosis.