Answer by  
                                                                                          sanityrose (2664)
                                                            
                          
                          
                                                          Many women experience an outbreak of cold sores during menstrual cycles and pregnancy. This is due to the bodies response to a weakened immune system, change in hormone levels, and stress. Cold sore are a form of Herpes simplex and it's estimated that 80% of the U.S populations is infected.