The luteal phase of the menstrual cycle follows ovulation. During this phase, which lasts about 14 days, levels of luteinizing hormone and follicle-stimulating hormone decrease and levels of progesterone increase. A new menstrual cycle begins when fertilization has not occurred. Then, the corpus luteum degenerates and levels of progesterone and estrogen decrease, causing the lining of the endometrium to degenerate and shed. If pregnancy has occurred, the corpus luteum starts to produce human chorionic gonadotropin, a hormone that sustains the corpus luteum, which continues to produce progesterone until the fetus can produce its own hormones.
Pregnancy tests detect increased levels of human chorionic gonadotropin.
Ovulation and Infertility About one-quarter of women with infertility problems don t ovulate normally, and some may not ovulate at all. Therefore, determining whether ovulation has occurred is an important part of any infertility evaluation. If you have regular menstrual cycles, usually ranging from about 26 to 35 days, you are most likely ovulating. Some women have a clear mucous discharge around the time of ovulation, while others feel mild abdominal discomfort on the same side as the ovary that released the egg. Still other women experience breast swelling or increased acne.