Herpes simplex virus type-2 infection in pregnancy: no risk of fetal death: results from a nested case–control study within 35,940 women

Abstract

Objective The aim of this study was to assess the association of fetal death with herpes simplex virus type-2 (HSV-2) antibody status during pregnancy: 1. presence of antibodies in first trimester; 2. appearance of antibodies (incident infection); 3. increase in antibody titre; and 4. loss of antibodies. Design Prospective study. Population The source population was a cohort of 35,940 pregnant women in Norway. Methods Nested case–control study within the cohort. Cases were all women in the study population who experienced a fetal death after the 16th weeks of gestation ( n = 281), and controls were 961 randomly selected women with a live born child. Main outcome measures HSV-2 antibody status. Results Twenty-nine percent (82/281) of women with a fetal death and 27% (256/961) of the controls had of HSV-2 antibodies present in the first trimester (odds ratio 1.1, 95% CI 0.8–1.5). HSV-2 antibodies appeared in 2% (3/136) of initially seronegative cases and 3% (16/623) of the controls during pregnancy (odds ratio 0.9, 95% CI 0.2–3.0). An increase in HSV-2 antibodies occurred in 4% (2/55) of initially seropositive cases and 7% (16/231) of the controls (odds ratio 0.5, 95% CI 0.1–2.3). Loss of HSV-2 antibodies in initially seropositive women was not associated with fetal death, 42% (23/55) of the cases and 45% (104/231) of the controls seroreverted (odds ratio 0.8, 95% CI 0.5–1.6). Differences in follow up time, age and parity were controlled and did not influence the comparisons between cases and controls. Conclusion This study provides no evidence of an association between HSV-2 infection during pregnancy and fetal death.