Is a girl more fertile before or after her period?

Not usually: You are fertile during ovulation which occurs at the middle of the cycle if your cycles are 28 days or 14 days before your period , so if your cycles are 35 days you would thoertically ovulate day 21, if you ovulate, which some women never ovulate or some women can ovulate every other month or every 3rd month , you can get an ovulation kit and it will show when and if u are ovulating.