ZocdocAnswersWhy is a girl's period delayed?

Question

Why is a girl's period delayed?

My younger sister is nearly 16 and she just told me she has never had her period. Could this be the result of some kind of development problem, or some kind of disease? I'm worried about her, but she doesn't want to see a doctor.

Answer

It sounds like your sister may have primary amenorrhea, the technical term for delayed development of her periods. The definition of primary amenorrhea is the lack of secondary sexual characteristics (such as the development of breasts) by age 14, or the lack of her first period by age 16. If your sister has some breast development, then she should be evaluated when she turns 16. If she does not have any breast development, she should be evaluated now. The best type of physician to see for this type of problem is an endocrinologist. Primary amenorrhea has many different causes. If your sister is very thin, or exercises a lot regularly, this can delay her period from starting. If this is the case, she will need to gain some weight. Other causes include a problem known as mullerian agenesis where the uterus and fallopian tubes fail to develop before being born. Genetic causes such as Turner's syndrome (most common) and androgen insensitivity syndrome are also possible. I would really encourage your sister to see a doctor. If she refused to see an endocrinologist when she turns 16, then she should at least schedule an appointment to see her pediatrician or family doctor now. Good luck.

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