Objective: To determine the risk for genital herpes and asymptomatic herpes simplex virus (HSV) shedding in late pregnancy and delivery in a population of HSV type 2 (HSV-2)-seropositive but previously asymptomatic pregnant women.
Design: A prospective inception cohort study.
Participants: A total of 1355 pregnant women with no history of genital herpes referred from three private obstetrics practices between November 1985 and June 1988.
Main Outcome Measures: Confidential questionnaires evaluated sexual risk factors in relation to HSV-2 serologic status as determined by Western blot analysis. Herpes simplex virus shedding was determined by viral culture of the cervix and vulva and of any suspicious lesions.
Results: Antibody to HSV-2 was detected in 439 of 1355 pregnant women (32%) with no history of genital herpes. Asymptomatic HSV shedding was detected in 5 of 1160 cultures (0.43%) obtained in late pregnancy and during delivery. A first episode of clinical genital herpes was recognized by 43 of 264 HSV-2-seropositive women (16%) during their pregnancy.
Conclusions: Serologic evidence of unknown HSV-2 infection was common in pregnant women without a history of genital herpes. Asymptomatic viral shedding in these women occurred at a rate similar to that seen in women with symptomatic genital HSV-2 infection. To improve recognition of genital herpes near term, obstetricians should counsel pregnant women about the high prevalence and mild and diverse symptoms of genital HSV-2 infection.