Usually it will last one to seven days, but occasionally it will last longer. Once your female hormones and organs are completely mature, you will probably bleed about the same amount of time every month, for three to seven days. For the first one to four years, your menses may come very irregularly, every few weeks to every few months. During this time, the female hormones and organs are continuing to mature. Once the female organs completely mature and an egg begins to come out from the ovary regularly, most people will bleed every 21 to 35 days.
Some women continue to have irregular menses throughout their lives.
If the egg is fertilized by a sperm from a man, a baby will begin growing in the uterus and the woman will not have a menstrual period. Taking a bath, swimming in a pool or in the ocean will not cause an infection or any harm to you while you are on your menstrual period. The Honolulu Advertiser, a division of Gannett Co .