Background:
A recent large study in the US suggests that infants born to women seronegative for herpes simplex virus (HSV) infection may be at higher risk for neonatal herpes.

Objective:
To determine seroprevalence of HSV type 1 (HSV-1) and type 2 (HSV-2) in a national sample of pregnant women.

Method:
National Health and Nutrition Examination Survey (NHANES) 1999-2002 is a nationally representative survey of civilian non-institutionalized US population. As part of this survey, serum samples were tested for antibodies to HSV-1 and HSV-2 using type-specific immunodot assays, and pregnancy tests (urine and serum) were performed for female participants 12-59 years of age.

Result:
This analysis included 626 pregnant women. The mean age was 27 years and the median number of lifetime sex partners was 4. Overall, 28% of pregnant women were seronegative, 63% seropositive for HSV-1, and 22% seropositive for HSV-2. HSV seroprevalence differed by race-ethnicity, with non-Hispanic whites more likely to be seronegative compared with other racial-ethnic groups (40% versus 11%, P<0.001). The number of lifetime sex partners was also associated with serostatus: 39% of those with 1-2 partners were seronegative, compared with 20% of those with >=3 partners. Based on serostatus-specific neonatal herpes rates from the literature and the serostatus distribution in NHANES 1999-2002, the rate of neonatal herpes is projected to be 33/100,000 live births in the US, corresponding to 1,300 cases per year. The projected rate is 40% higher in non-Hispanic whites than in other racial-ethnic groups.

Conclusion:
The seroprevalence of HSV-1 and HSV-2 is high in pregnant women in the US. Babies born to non-Hispanic white mothers appear to be at greater risk for neonatal herpes.

Implications:
Efforts to prevent neonatal herpes should include populations traditionally regarded as low risk for HSV infection.