Menstruation menarche has changed little in the United States since the 1950s. Menstruation is the most visible phase of the menstrual cycle and its beginning is used as the marker between cycles. The first day of menstrual bleeding is the date used for the last menstrual period (LMP). 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 31 days in adults (an average of 28 days). Perimenopause is when fertility in a female declines, and menstruation occurs less regularly in
Menstrual cup find a larger cup uncomfortable. Length also needs to be considered: if a female's cervix sits particularly low, she may want to use a shorter cup. Capacity is important to women who have a heavier flow. The average menstrual cup holds around 20 ml. Some cups are designed to be larger and hold 37–42 ml. However, all cups currently available have a larger capacity than a regular tampon, which is 10–12 ml. A final consideration in selecting a menstrual cup is firmness or flexibility. Some companies offer a range of firmness levels in their cups. A firmer cup pops open