ZocdocAnswersBy what age should one start their period?

Question

By what age should one start their period?

My daughter is 15 and she still hasn't had her first period, to my knowledge. I really don't want to be overbearing, but this seems pretty abnormal . I got my first period at a much younger age. What kind of problems could cause this sort of delay ?

Answer

The normal age for girls to start their periods is between 11 and 14. There are reports of girls starting before 10, but this is usually secondary to obesity. Girls that have not started their cycle by age 15 technically are delayed, but this does not mean that they necessarily have something wrong with them. Let me explain. During sexual development, genetics, age, and a girl's body mass index integrate to determine when a menstrual cycle begins. The last factor is the most important with girls that are only a year late starting their periods. If you daughter is an active athlete, exercises regularly, or is exceptionally skinny, then her body may not think its ready to start her cycle. This is because the body needs a certain amount of fat stores to insure that it could support a child if a women were to become pregnant. For this reason, some gymnasts and cross country runners do not have their first period till age 17. However, there are other causes of menstrual delay. The only way to differentiate the different types of delay is for a physician to perform a detailed physical exam and certain blood tests. I would bring her to see either her pediatrician or family doctor. He or she will know what the next best step is. Good luck.

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