You may not be ovulating at all.
When women spend a lot of time together, their cycles end up running concurrently... with the one woman in the group who is currently fertile. If she has no intention of getting pregnant, isn't involved with anyone or has been sterilized, she's (accidentally, but it makes sense for a small village to not have all the women pregnant at the same time) repressing the ovulation of most of the women around her.
It's why 'infertility' happens to so many nurses and teachers (often working with many women in one building), and why clusters of pregnancies suddenly happen (when the woman driving the cycle goes on extended vacation or retires or whatever).
It also neatly explains why so many women adopt and while on maternity leave (and not working with that woman anymore) get pregnant 'out of nowhere.'
at 1:44 AM on Oct. 2, 2009