Re: stopping your period
...technically....'safe' means less likely :) you usually ovulate around a week after your period to a week before your period. This means you are probably LESS likely to get pregnant right after or right before your period. However, your period might not be that regular. Ovulation can occur at any time, even while you are on your period.
I got this from some website....
"There is no 'safe' time. Sperm can live in your body for up to 5 days waiting for you to ovulate. Your egg will live for 12-24 hours. (And you're actually 'most' fertile on the day before and the day of ovulation. The day after there's not much of a chance.) Therfore, unless you know exactly when you're ovulating, you don't know when 'not' to have sex. Sex more than 48 hours after ovulation would be the only sex I'd consider if avoiding pregnancy. Every woman is different, and most women don't ovulate on the exact same cycle day every month. Through charting, you can pinpoint your ovulation day, and I personally have ovulated anywhere from 10 days after the first day of my period to 16 days after. That's a pretty wide stretch to leave to chance. USE protection."