Hi Doc..my Freind Hve Unprotected Sex With Her Husband At

hi doc..my freind hve unprotected sex with her husband at last july8,, she hve menstration at july1 until july7,she hve contact with her husband at july8 do u think they hve possibility that she is pregnant.bcos she is delayed now 3weeks but she try to use pt its negative.she isvery worried and paranoid now bcos she dont want now to hve pregnancy during to busy at work..thanks doc for advice