is there a possibility of getting pregnant even if it was the 4th day of menstrual cycle?
Yes - There is a possibility of getting pregnant at any point of your cycle, there is NO safe zone. It wouldn't be probable that you would ovulate at that point, but it's not impossible, it depends on your cycle.
But still.. you can get pregnant at any time during your cycle but at some point there is a higher chance of fertility. Around day 14 I think.
its actually a lot easier getting pregnant on your period then off.