menstrual cycle

So I'm taking anatomy this semester and I like to tell Shaun some things that I learn in class.

Me:  I didn't know that your blood in the menstrual cycle that comes out was for the baby.
Shaun: Huh? So It's like cleaning your pipes?
Me: Huh?
Shaun: So it's like cleaning out your pipes.
Me: No, I didn't know that the blood..
Shaun: Uh huh..
Me:  ...that comes out is to prepare for the baby.
Shaun:  Sooooo the baby eats the blood?
Me: WHAT?!?!
Shaun:  So the baby eats the blood?!?
Me:  [The blood] is the breaking down of the uterine wall..
Shaun:...
Me: Where do you think the umbilical cord is hooked up to?!
Shaun: So that's where they eat the blood?