[Brandye]

I do not think the decrease in fertility is nearly that great for most women but you are on to an important point.

In this context, the more important point is simply that as we mature we are less likely to take chances and are a bit more careful in our contraception. We often have questions here about missed or lost pills - from teens. The old joke was about the effectiveness of the diaphragm in the medicine cabinet. And by the time we reach our mid-20s we have learned to mean it when we say, "No condom, no sex."