Can Intercourse On The First Of The Period Increase Chances Of Pregnancy?

Hello,
I took postinor 2 while I had my period, a day after unprotected sex. Usually postinor 2 induces premature period in my monthly cycle.. within a week of taking it, I get my periods. But this time that has not happened. Is it because I was already having my period when I took the pill. Or could it mean that there are chances of pregnancy? Does having sex on the first day of one's period leader higher chances of pregnancy?