Snapshot A 27-year-old G3P0A2 comes to the outpatient office at 15 weeks of gestation and presents with exquisite vulvular pain and blisters. She said she had similar episodes prior to pregnancy for the last five years. On physical exam, there are vesicles on the left labia minora which are markedly tender to palpation. She has a positive chlamydial culture on her first prenatal visit that was treated with erythromycin tablets. Introduction Herpes simplex virus has potential for significant adverse impact on the fetus, neonate, or both Does not increase the risk of congenital malformations, but infectious sequelae are possible If active vaginal infection, then 50% chance of transmission to infant Presentation Symptoms mother painful ulcers infant seizures vesicles respiratory distress meningitis impaired neurological development Physical exam mother ulcers tender to palpation infant vesicles on scalp, face, and buttocks (if breech delivery) irritability and lethargy fever poor feeding seizures Differential Differential diagnosis of genital ulcers syphillis chancroid Treatment If lesions or prodromal symptoms are present at the start of labor cesarean delivery is indicated Acyclovir markedly reduces viral shedding and recurrent lesions at onset of labor patients with active genital lesions should be offered treament at 36 weeks of gestation Prognosis, Prevention, and Complications Prevention focuses on reducing vertical transmission cesarean delivery prophylactic acyclovir Complications neonatal herpes