how to tell my daughter about why women have periods?

If you feel uncomfortable talking about the menstrual cycle, or if you feel like you wouldn’t be a good enough teacher, you could always just pick up a book with the information you want her to have in it, and give it to her.

Tell her something like, “You’re growing up, and I want you to be ready, so here is a book with some things you might need to know. If you have any questions or if you want to talk about it, I’m here.”

That way she’ll be getting information from a reliable source (instead of friends or TV), and she’ll know you’re there for her.

tell her that we’re all like water balloons. Once a month we get filled with water, and we expel it like water coming out of the balloon. Tell her that they carry eggs like chickens.

You didn’t tell us the important info…how OLD is your daughter?? At an early age, telling them just enough to satisfy their curiosity is a good enough. But, if she has reached puberty, then you need to tell her everything and do it truthfully and factually. If she’s had her first cycle, then it’s time that she knows why and the reason behind it.