Hi everyone: I was talking with a friend who was "late," and so she took a pregnancy test. She was pretty surprised when I told her to wait until 10 days late or so because the tests aren't very accurate if you do it sooner. I then explained which phase of the menstrual cycle is longer when you're late, and I felt like I was teaching high school physical education class!

It got me wondering--how many women really don't understand when they ovulate?