Menstrual cycle The first period usually begins between twelve and fifteen years of age, a point in time known as menarche. They may occasionally start as early as eight, and this onset may still be normal. The average age of the first period is generally later in the developing world and earlier in developed world. The typical length of time between the first day of one period and the first day of the next is 21 to 45 days in young women and 21 to 35 days in adults (an average of 28 days). Menstruation stops occurring after menopause which usually occurs
Menstrual cycle than the developed world. The average age of menarche is approximately 12.5 years in the United States, 12.7 in Canada, 12.9 in the UK and 13.1 years in Iceland. Factors such as genetics, diet and overall health can affect timing. The cessation of menstrual cycles at the end of a woman's reproductive period is termed menopause. The average age of menopause in women is 52 years, with anywhere between 45 and 55 being common. Menopause before age 45 is considered "premature" in industrialised countries. Like the age of menarche, the age of menopause is largely a result of cultural and