The Hormone Series: Part I, Progesterone.

Estrogen and Progesterone function like a complex symphony working together to keep our bodies (and fertility) in a state of balance.

Progesterone is the dominant hormone in the second half or luteal phase of your menstrual cycle, and its role is to continue the work of estrogen in preparing the lining of your uterus for pregnancy*

If the egg you released is fertilized by a sperm + you become pregnant, the corpus luteum continues to produce progesterone until about 10 weeks of pregnancy. Then, your placenta takes over. If you do not become pregnant, then your corpus luteum dissolves, your progesterone levels drop, you get your period, and a new menstrual cycle begins. 

Author

Dr. Sam Najmabadi Dr. Sam Najmabadi is a member of the Society for Reproductive Endocrinology and Infertility (SREI). Members of SREI are a select group of physicians who are committed to providing excellence in reproductive health through education, research, and patient care. Membership is limited infertility physicians who have been certified by the American Board of Obstetrics and Gynecology (ABOG) as having special knowledge and proficiency in the specialty of obstetrics and gynecology and in the subspecialty of reproductive endocrinology and infertility. Fewer than 800 physicians have achieved this distinction. "My goal is to provide the highest quality fertility care in an environment full of compassion and support." -Sam Najmabadi, M.D.