|wait, aren't you confusing that with the "this is not consensual sex" talk?|
Because really, confusing the "facts of life" talk with the "no means no" talk really does fall in to the category of parenting fails.
And this is from a person who talks to her children about...everything... just... with a substantial amount of mindfulness that their childlike brains often take things more literally than initially intended (you learn this lesson relatively quickly, fortunately). That being the case, talking about "periods and babies" is something that can happen gradually, building on knowledge so that they're not completely overwhelmed with one hideous (and let's face it, mutually embarrassing and awkward) talk.
Or, you know, you can follow her advice.