When Should My Periods Start?

What Is The Average Age For A First Period?

A girl's first period (or menstrual cycle) is technically called menarche. In the United States and other Western countries the typical age for a girl to have her menarche is twelve and a half. However some girls can start as young as 9 while others may start as late as 15. Generally a girl tends to get her periods within 2 years of her breasts starting to develop. If you are aged 13 or 14 and your period hasn't started yet, don't panic, it's quite normal. In fact it may even be good news because girls who start their first period after the age of 14 have a much lower chance of developing endometriosis (a disorder which causes pelvic pain and affects up to 10 percent of women) when they are older. If your periods have not started by the age of 16 it is worth talking to a doctor who may say you have primary amenorrhea. Again, this is nothing to be concerned about. The doctor will carry out a pelvic examination to check there are no obvious problems. If you are given the all-clear, no further tests or treatment are usually necessary unless your periods have not started by the age of 18.

Does This Mean I Can Get Pregnant?

Unlikely but still possible. Just because a girl gets her menarche, it does not mean she has started ovulating yet. Ovulation is where eggs in the ovaries are released so that they can be fertilized by sperm to produce a baby. If a girl has a period, but there is no ovulation, she is having an anovulatory cycle. This means she can't get pregnant. 80 percent of girls have anovulatory periods in the first year after menarche. This reduces to 50 percent by year 3 and 10 percent by year 6. That said, not every girl is the same. Occasionally some will ovulate BEFORE they even have their first period. This means, if they are sexually active before menarche they could become pregnant.

What Can Make A Period Start Earlier?

Studies show that girls are statistically more likely to have their first period early if any of the following apply:
- they are obese and don't exercise much.
- they were not breastfed as a baby.
- they were born with a low birth weight.
- their father is absent from the home since early childhood.
- there is constant stress and fighting in the home.

Related Questions
How can I relieve period cramps?
What can cause a change in my monthly cycle?

• Need more information about periods? See: Guide To Menstruation
• Got another question? See: Womens Health Questions

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