What causes a herpes outbreak at 39 weeks pregnant?

Herpes pregnancy: Pts with a history of genital herpes should undergo a careful perineal examination at the time of delivery.Vaginal delivery is indicated if no signs or symptoms of hsv are present.Active genital hsv in patients in labor or with ruptured membranes is an indication for c/s.Reactivation occurs in 50% of patients within 6 months of the initial outbreak.Whether pregnancy alters the rate is disputed.