How Do You Know You Are Pregnant?

A group of 7th or 8th grade girls asked me this question.  I told them I got a pregnancy test and "peed" on a stick. 

They asked me how that worked.  So I told them that there are hormones in your body that help you grow and hormones that help the baby grow.  The test can find those hormones. 

But then the girls got to the real question they were trying to find out.  "How did you know you needed to take the test?"  So, I asked them, "Do you know how someone gets pregnant?" They told me they did, I didn't verify, it didn't matter because what I was going to say next didn't matter if they really knew how or not.

I said, "Well, my whole life I never did any thing that could get me pregnant.  Then when I was old enough, married, and mature enough to be a parent, I did those things that could get me pregnant."

Not sure if I answered the question they wanted but I gave them a teaching moment and boy was I grateful that I did not have to lie.  I was completely honest with those girls.