Talking about the miracle of menstruation is a necessary part of helping your daughter make the transition from little girl to young woman. While the thought of discussing such a personal matter can leave you feeling a bit apprehensive, the conversation doesn’t have to leave you tongue tied.

Just keep in mind the three Ps of the period talk: proactivity, preparedness, and portion size.

Proactivity: Imagine suddenly discovering that you’re bleeding and not understanding where the blood’s coming from or why it’s happening. That would be pretty scary, wouldn’t it? Well, that’s what your daughter could experience the day she starts her first period unless you tell her beforehand what to expect.

American girls begin to menstruate, on average, at age 12 or 13. Although some girls are as young as 10 and others are as old as 15 or 16. Breast development and pubic hair often precede a girl’s first period by a year or two, so when you see these initial signs of adolescence in your daughter, that’s the time to begin explaining menstruation.

Since your daughter will probably ask about these other changes to her body as they begin to happen, they can provide opportune moments to tell her that menstruation will be the next, perfectly natural change her body will undergo on its way to womanhood.

Preparedness: You might want to give yourself a small refresher course on the female reproductive system. There are plenty of books and online resources to bring you up to speed on the basics of reproductive anatomy and the menstrual cycle. For instance, young girls just beginning their periods often have irregular cycles for the first few years. A fact you both need to know.

In addition to basic information about menstruation in a teenage girl, these resources can provide diagrams that will help you teach your daughter what her reproductive organs look like and where they’re located in her body.

While you need to tell your daughter the basics of female anatomy and the critical fact that her first period heralds her ability to become pregnant, she’ll likely be more interested in other aspects of menstruation, including: when she’ll start, how much she’ll bleed, if it’ll hurt, if she’ll be able to swim and play outside, how will she use tampons and pads, and will everyone be able to tell she’s on her period.

Portion size: If you tell your daughter every last thing she needs to know about her period in one, long explain-a-thon, you risk overwhelming her. Since you’re beginning your conversations many months before her first period arrives, you'll have plenty of time for easier-to-absorb, smaller talks.

Ask your daughter’s teacher if they are covering adolescent health topics in class. If they are, you can use the information to segue into a conversation about menstruation with your daughter. You can begin by asking her what she’s learning and if she has any questions about it.

If you’re watching TV or looking through a magazine together, you can use an ad for maxi pads or premenstrual syndrome relief medication as a launching off point to discuss one particular aspect of having periods.

Unless she asks, you can save the talks about keeping a period calendar and what to do if she stains her clothes for another time.