Ovarian aging refers to the natural decline in the quantity and quality of a woman's ovarian reserve as she ages. This process typically begins in a woman's late 20s and accelerates in her late 30s and early 40s, leading to decreased fertility and an increased risk of chromosomal abnormalities in eggs. As women approach menopause, usually occurring between ages 45 and 55, the ovaries produce fewer hormones, such as estrogen and progesterone. This hormonal shift can result in various symptoms, including irregular menstrual cycles and hot flashes, marking the end of a woman's reproductive years.