strange menstrual cycles?

Question

my girl friends peroid was gone for a week and then came back this morning. we have had sex (protected) three times since her period and this is not the first time this has happened

o and to add her, age its 21 if that helps.

Answer 1

Sometimes being stressed about something can cause the period to be delayed by a week but because this isn't the first time this has happened I would recommend that she see her doctor for further evaluation of the situation to see what they think could be going on.