I'm Pregnant And I Don't Know Who My Child's Father

I'm pregnant and I don't know who my child's father is. Before I got pregnant I use to jot down when I had unprotected sex. It was very rare that I had unprotected sex. My due date is October 23, 2016. So I conceived on January 31st and had sex with a friend the day before which was January 30th. Does that mean he is my child's father