[Mrs. Don-o]

This is good for achieving pregnancy as well, by choosing intercourse at the most-fertile times.

Experience seems to show that NFP couples end up having more kids anyway, because over the years, they end up wanting more kids.

It certainly allows for choosing to optimize reproductive success across the fertile years --- unlike, say, sterilization.

[AC Beach Patrol]

If used for this purpose I take back my sarcastic comment.