ObjectiveTo determine if the signs and symptoms of genital herpes in pregnancy accurately identify primary genital herpes infections using serologic testing for final classification.MethodsTwenty-three women with clinical signs and symptoms suggestive of primary genital herpes infections in the second and third trimesters of pregnancy were subsequently cultured and tested serologically (for herpes simplex virus type 1 and herpes simplex virus type 2 antibodies) and clssified as having true primary (no herpes simplex virus type 1 or type 2 antibodies), nonprimary (heterologous herpes simplex virus antibodies present), or recurrent (homologous antibodies present) infections.ResultsOnly one of 23 women with clinical illnesses consistent with primary genital herpes virus simplex infections had serologically-verified primary infection. This primary infection was caused by herpes simplex virus type 1. Three women had nonprimary type 2 infections, and 19 women had recurrent infections. Among culture-proven recurrent infections, 12 were caused by herpes simplex virus type 2 and three by herpes simplex virus type 1. Only one infant was born preterm, and no clinically significant perinatal morbidity was observed.ConclusionCorrect classification of gestational genital herpes infections can be accomplished only when clinical evaluation is correlated with viral isolation and serologic testing using a type-specific assay. Severe first episodes of genital herpes infections among women in the second and third trimesters of pregnancy are not usually primary infections and are not commonly associated with perinatal morbidity.