Progesterone is a steroid hormone that plays a crucial role in the female reproductive system and pregnancy. This test measures progesterone levels in the blood to evaluate ovarian function, confirm ovulation, and assess pregnancy health. Progesterone is primarily produced by the corpus luteum after ovulation and by the placenta during pregnancy. It prepares the uterine lining for implantation of a fertilized egg and maintains pregnancy by preventing uterine contractions. Progesterone levels rise after ovulation and remain elevated during the luteal phase of the menstrual cycle. Low progesterone levels can indicate problems with ovulation, luteal phase deficiency, or threatened miscarriage. This test is commonly used to evaluate infertility, confirm ovulation timing, assess the adequacy of the luteal phase, and monitor pregnancy health. Understanding progesterone levels is essential for fertility evaluation and early pregnancy management.