The amount of blood varies, usually starting out light, then heavy, then light again. Use pads or tampons to absorb the flow. Menstruation is just one part of the menstrual cycle, in which a woman's body prepares for pregnancy each month. A cycle is counted from the first day of one period to the first day of the next. An average cycle is 28 days, but anywhere from 23 to 35 days is normal.
Some women feel a period coming days before they get it.
Others are hardly aware they have it. Friends who compare notes about their periods will probably find that menstruation-the monthly shedding of the lining of the uterus, or womb affects each of them a little differently, both physically and emotionally. The menstrual cycle has its ups and downs of hormones, and different people react differently to hormonal swings. Just before and during menstruation, levels of the female hormones estrogen and progesterone are low. Just crummy might mean cramps, sore breasts, backache, headache, nausea, and feeling tired.