Well, I've often heard that "mid-cycle" fertility idea is like a fable... I've heard of women getting pregnant/being fertile even during their periods. I'm not sure if our bodies are as predictable as some would like to hope.......
here's a site I found
When does pregnancy occur?
The human body is so complicated and mysterious....... it's odd to think that we don't even know how our own selves really work!
mandy