What is a major change tracked through the menstrual cycle?

The menstrual cycle is primarily regulated by hormonal changes in the body, and these hormonal levels fluctuate in a predictable manner throughout the cycle. The key hormones involved include estrogen and progesterone, which are produced by the ovaries and play vital roles in regulating ovulation and the menstrual phases.

At the beginning of the cycle, estrogen levels rise as follicles in the ovaries mature. This peak stimulates the release of luteinizing hormone (LH), leading to ovulation. After ovulation, progesterone levels increase to prepare the uterine lining for a potential pregnancy. If pregnancy does not occur, both hormone levels drop, resulting in menstruation. These distinct hormonal shifts are crucial for understanding the menstrual cycle's physiological processes, such as ovulation and the preparation of the endometrium.

Other options, like bone density, blood pressure, and hair growth rate, do not have a direct or significant correlation with the cyclical changes that occur specifically during the menstrual cycle in the same way that hormonal levels do. Thus, tracking hormonal levels provides essential insight into the reproductive health and menstrual function of individuals.