Whether you realize it or not, every day you lose some hair. Your body then replaces it with some new strands as part of the many renewal processes that are built into our systems. As you age, the reappearance of new hair gradually slows. This phenomenon is more noticeable in men, whose “male-pattern baldness” is genetically determined and can begin as early as age 20. For women, hair normally thins after age 50, and significant hair loss before that age is rare. Hair loss can also be tied to a wide variety of conditions not related to your family history, such as nutritional deficiencies, side effects of illnesses or a particular drug, child birth, hormonal shifts, or periods of increased stress.