Menstruation is the shedding of the (endometrium). It occurs on a regular basis in reproductive age females of certain mammal species. Overt menstruation (where there is bleeding from the vagina) is found primarily in humans and close evolutionary relatives such as chimpanzees.[1] The females of other placental mammal species have estrous cycles, in which the endometrium is reabsorbed by the animal (covert menstruation) at the end of its reproductive cycle. Many zoologists regard this as different from a "true" menstrual cycle.

How Often Does a Girl Get Her Period?

Just as some girls begin puberty earlier or later than others, the same applies to periods. Some girls may start menstruating as early as age 10, but others may not get their first period until they are 15 years old.

Timing Is Everything

It's probably best to avoid "The Talk" about menstruation. Instead, try to spread it out into lots of smaller conversations — education about how the human body works should be continuous. Otherwise, too much importance is placed on a single discussion and the information can be overwhelming. In other words, kids reaching puberty should already know what a penis and vagina are.

Problems With Your Cycle

Having your period can be a real pain, in more ways than one. If you suffer from menstrual cramps, read up on why women feel such pain every month. You'll also get some handy tips on how to get rid of those menstrual cramps. But cramps don't only occur when you have your period. Women who notice period-like cramps half-way through their cycle may have mittelschmerz, a type of cramping that happens when you ovulate. However, if your menstrual cramps are so intense that you regularly experience severe pain, then you may actually have dysmenorrhea.

What if my period is late or I missed my period?

Sometimes a period may come late or be missed for the month. Frequently, a woman's first thought is that she is pregnant. Yes, that could be the case, but there are times when a woman may be late or miss her period for other unsuspected reasons.

Everyone's different

Your daughter may worry that she's not normal if she starts having periods before — or after — friends her age do, or if her periods aren't like those of her friends. But menstruation varies with the individual. Some girls have periods that last for two days, while others have periods that last more than a week. It can even vary this drastically from month to month in the same girl. The amount of blood lost each month can vary, too, from a few tablespoons to more than a half cup.

Talking About Menstruation

If your daughter is approaching menstruation, you can make the whole process easier and more comfortable for her (and you!) by talking to her openly about what it means to have your "period." Dads, don’t despair! You have an important role to play as well, either as a single Dad and the primary parent, or as a partner in guiding your daughter through puberty and adolescence.