Learning about Menstrual Periods before Punctuation Marks

In March, my daughter, son, and I went to a friend's wedding. At one point I needed to go to the bathroom. I left my son with my sister. Charis decided she needed to go potty as well-but did not tell me she was following me to the restroom. I went in the stall, locked the door, and breathed a sigh of relief, "Peace at last." Then I noticed Charis doing to arm crawl to get in my stall. I was about to make her go to her own stall... until I heard a handful of college students come into the bathroom, laughing and chatting.

"Mom!!! Why's there RED blood in the toilet?" Silence. You could hear a pin drop. (Yes, I realize that is probably an overused cliche, but who cares?)

"Charis, mama has her period."

"Is that like an owie?"

"No Charis. It's not an owie. It happens once a month when mama's not pregnant. It's the body's normal way of shedding the lining of the uterus. The blood comes out through mommy's vagina. I means there's no baby inside me."

Since then, I've had my period two more times times, and each time Charis says, "There's NO baby inside my mommy."

Some people might disagree with me teaching my 4 year old about menstrual periods before she learns about the punctuation mark. But I'm teaching her because, I want..

Charis (and my other children) to learn about it from me-not her friends. Friends can be full of misinformation or too much information. 

To be honest with her. My daughter saw something (somewhat) out of the ordinary and thought something was wrong with me. I did not want to brush her fears aside. She needed reassurance that mommy was okay. Did I go into all the detail that I could have covered? No. I answered the questions about what she saw-that was it. She will get more detail later, but for now, her curiosity is satisfied.

Her to realize it's normal-and that it's not gross. For most females, the menstrual cycle is something that they will have about once a month. It's a fact of life. I do not want my daughter to think of her menstrual cycle as gross. It is part of biology and that she is "fearfully and wonderfully made" (Psalm 139:14).

When did your children learn about menstrual cycles?