Cytomegalovirus antibody status at 17-18weeks of gestation and pre-eclampsia: a case-control study of pregnant women in Norway

Objective: To assess the association between maternal cytomegalovirus (CMV) antibodies in mid-pregnancy and pre-eclampsia. Design: Nested case-control study. Setting: Pregnancies registered in the Norwegian Mother and Child Cohort Study (MoBa): a large population-based pregnancy cohort (1999-2006). Sample: A cohort of 1500 women with pre-eclampsia and 1000 healthy pregnant women. Methods: Plasma samples and pregnancy-related information were provided by the MoBa. Antibody status (CMV IgG and CMV IgM) and levels (CMV IgG) at 17-18weeks of gestation were determined by enzyme-linked immunosorbent assay (ELISA). Main outcome measure: A diagnosis of pre-eclampsia, as defined in the Medical Birth Registry of Norway. Results: There was no evidence of an effect of CMV IgG seropositivity on the likelihood of developing pre-eclampsia, and CMV IgG antibody levels among women who were seropositive did not differ between groups. Adjusted for maternal age, parity and smoking, the odds ratio for pre-eclampsia in women seropositive for CMV IgG was 0.89 (95% CI 0.74-1.05; P=0.17). The proportions of women who were seropositive for IgM did not differ between women with pre-eclampsia and women who were healthy (P=0.98). Among nulliparous women, the proportion of women who were seropositive for CMV IgG was slightly lower among women with pre-eclampsia (53.5%) than among healthy women (59.8%) (P=0.03). Subgroup analyses were performed for women with early or late onset pre-eclampsia, with preterm delivery and/or with neonates that were small for gestational age, but antibody status did not differ between pre-eclampsia subtypes and controls. Conclusions: The presence of maternal antibodies to CMV was not associated with pre-eclampsia in our study. The results suggest that CMV infection is unlikely to be a major cause of pre-eclampsia. [PUBLICATION ABSTRACT]