What stimulates a change in progesterone levels in humans?

Progesterone levels in humans are primarily stimulated by the luteinizing hormone (LH) released from the pituitary gland, particularly during the menstrual cycle. After ovulation, the corpus luteum forms and secretes progesterone in response to LH, which helps prepare the uterine lining for potential implantation of a fertilized egg. Additionally, during pregnancy, the placenta produces progesterone to maintain the uterine environment. Factors such as stress, hormonal imbalances, and certain medications can also influence progesterone levels.