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Reviewed by the Faculty of Harvard Medical School


For girls, the start of menstruation (commonly referred to as a period) is one of the most commonly identified physical happenings of puberty, that time when a child's body goes through changes in becoming an adult's body. Menstruation is the periodic flow, usually every month or so, of blood-containing fluid from the uterus (womb) when it is not needed to support a pregnancy. Like many of the changes associated with puberty, starting menstruation can be confusing for girls. Some girls can't wait to get their period, while others may feel afraid or anxious. It is important for you to talk with your daughter about menstruation well before she gets her period, so she knows what to expect and to ease any fears and anxieties about it.

A good time to talk about menstruation is right around the beginning of puberty, when a girl's breasts begin to develop. Menstruation will usually start one and a half to two years later. Just as there is a range of ages when girls begin to go through puberty (ages 8 to 14), there also is a range of ages when girls get their first menstrual period (ages 9 to 16).

Exactly when a girl will get her period depends on when she started puberty and also depends on her health and family history. If a girl's mother started menstruation at an early age, then she is likely to start puberty and get her period at an early age, too. Likewise, a girl whose mother got her period later will probably start puberty and get her period later. Although it can be normal for some girls to get their periods later than other girls, it is important that they get it within a reasonable time frame. If your daughter does not get her period by her 17th birthday or does not show any signs of puberty by age 13, you should call her pediatrician for an evaluation.

When talking with your daughter about menstruation, let her know what to expect.

  • Many girls notice a clear discharge from the vagina for about six months to one year before getting their first menstrual period. This discharge is normal and should not worry your teen. However, if the discharge is white or yellow, smells bad, or is very itchy, it could be a sign of infection and you should call her pediatrician.
  • It is common for periods to be "irregular" for the first six to 12 months after a girl gets her first period. This could mean getting two periods in one month or skipping several months in between periods. It usually takes the body some time to sort out all of the hormonal changes that are happening.
  • After a number of months, the menstrual cycle should become more regular. On average, most girls will get their period every 28 days, although this can vary between every 21 and 35 days.
  • It is common for the amount of time a girl has her period (how many days she has some bleeding from her vagina) to vary. Some girls will have their period for just two to three days, while others will have it for six to seven days.
  • The amount of fluid also can vary. It often is heaviest for the first two to three days and then gradually slows down. It is common for girls to need to change their pads or tampons every two to three hours during the first few days when the flow is the heaviest. However, if your daughter needs to change a pad or tampon every hour, this may indicate that she is losing too much blood and you should call her pediatrician.
  • Some girls get menstrual cramps (pains in the lower part of the abdomen and back) a few days before and/or during their periods. Taking a hot shower or bath, drinking a hot cup of tea, or using a heating pad or hot water bottle can make cramps feel better. Over-the-counter medications such as acetaminophen, ibuprofen and naproxen also are helpful. If your daughter has cramps that do not get better with these traditional treatments or that cause her to stay in bed and miss school, you should call her pediatrician.
  • Some girls feel depressed, easily irritated, or moody for a few days or for as long as a week before their periods. They also may feel bloated or puffy and their breasts may become swollen and sore. These emotional and physical changes, referred to as PMS (premenstrual syndrome), are due to changing levels of hormones and usually go away when their period starts.

Make sure your daughter knows that when a girl gets her period, it means she can get pregnant. When talking about menstruation, remember also to talk to her about sex and about preventing pregnancy and sexually transmitted diseases. Boys should be taught about menstruation, too, as part of basic sex education.

It is important that you make sure your daughter is prepared for her first (and later) periods. This not only means that she is mentally prepared, but also means that she has all the necessary supplies she might need.

Explain to your daughter that she must wear something to absorb the menstrual fluid. All teens can safely use many brands of sanitary napkins and tampons, which are readily available at most drug stores and grocery stores.

Sanitary napkins are disposable pads that are placed on the lining of the underwear. They are available in many shapes and sizes; your daughter may want to try out several different brands. Pads should be changed at least every four hours to minimize the chance of leaking and odor. It is common to need to change a pad every two to three hours for the first few days of a period, when flow is the heaviest. Remember, if your teen needs to change her pad every hour, you should call her pediatrician right away.

Tampons are absorbable pieces of cotton that are inserted into the vagina to soak up the menstrual flow. Since they are available in different shapes and sizes, your daughter may be more comfortable starting with a brand that is specially designed for young girls. Tampons should also be changed every four hours to lessen the chance of leaking and also for infection. Toxic shock syndrome (TSS) is a rare, but dangerous bacterial infection that has been associated with tampons left in the vagina for longer than eight to 12 hours. As long as tampons are changed frequently, the risk of TSS is very low.

The decision whether to use pads or tampons should be your daughter's choice. Many girls prefer tampons because they are not as messy as pads. Tampons also make it easier for girls to go swimming or to wear tight-fitting clothes such as bathing suits or leotards. Some girls prefer pads because they are not comfortable putting a tampon into their vagina.

Your daughter should carry a small bag in her purse or backpack with pads and/or tampons. Many girls wear panty liners around the time they expect to have their period. Let your daughter know that she can always go to the school nurse if she happens to get her period and does not have any supplies with her. Most school nurses are prepared for this common emergency.

Reassure your daughter that all women get periods and she is not alone. Tell her that menstruation should not get in the way of exercising, having fun or enjoying life. Let her know that you are there for her if she has any questions. She also can talk with her friends, sisters and relatives who have already gone through the experience and read books about puberty for teens.

Last updated May 29, 2011