Websites on missed periods?

Here is a website I found when I google searched “irregular period.” It seems to have some of the information you’re looking for.

It’s not uncommon to have an irregular period. I never had a particularly regular period and eventually went on birth control when I was 13 or 14 (long before I was sexually active) to regulate it. I know many girls who have gone through the same thing.

If your little sister is still worried about it even after seeing this information, ask her to talk to a parent or a school nurse about it. There’s certainly nothing to be ashamed of!

This one from Kids Health is very good:

“But a girl’s body may not follow this schedule exactly. It’s not unusual, especially in the first 2 years after menarche, to skip periods or to have an irregular menstrual cycle.”

American Girls has a book called The Period Book that is well worth owning with young girls.

sometimes hospitals have classes about girls development, check the local hospitals. The classes are thought by a female doctor and you can ask all the questions you have.

You might want to rule out PCOS, especially if she devolops cysts on her ovaries or has a lot of acne. But, most likely her body just isn’t in its regular rhythm yet.

it’s quite common and usual to have irregular periods in your early years . . . i had them too.

I just wanted to second @BarnacleBill‘s suggestion of the American Girl Period Book. There’s also a book by American Girl called The Care and Keeping of You, which is awesome. This is the book that every woman wishes she had as a girl. It explains all the body changes girls go through in terms that they can understand, and it also talks about other things that girls have to deal with (body odour, friend problems, that kind of thing). I’m sure any girl facing puberty would benefit from it.