Menstrual irregularities are a common condition that women may experience at different stages of life. A menstrual cycle that is shorter or longer than usual, delayed or more frequent periods, or bleeding that is heavier or lighter than expected may be considered irregular. While occasional changes do not always indicate a significant health problem, recurring irregularities should be evaluated to determine the underlying cause. One of the most common causes of menstrual irregularities is hormonal changes. Changes in hormone levels during puberty, the postpartum period, and the perimenopausal period can affect the menstrual cycle. In addition, conditions such as polycystic ovary syndrome (PCOS), thyroid disorders, significant weight changes, severe stress, inadequate nutrition, and excessive exercise may also lead to changes in menstrual patterns. Birth control methods, certain medications, and gynecological conditions affecting the uterus or ovaries can also contribute to menstrual irregularities. For women who may be pregnant, a delayed period should first be evaluated for the possibility of pregnancy. If menstrual irregularities occur frequently, persist for an extended period, or are accompanied by symptoms such as heavy bleeding or severe pain, consultation with an obstetrics and gynecology specialist is recommended. Following an examination and any necessary tests, the underlying cause can be identified and an appropriate, personalized treatment plan can be developed.