Clinical factors associated with cytomegalovirus shedding among seropositive pregnant women

Abstract

Background: Both neighborhood disadvantage and close contact with children have been associated with seroprevalence of cytomegalovirus in pregnancy. However, it is unknown which individual factors influence whether seropositive women are likely to have ongoing viral shedding.

Objective: This study aimed to define the frequency of and risk factors for ongoing maternal cytomegalovirus shedding across gestation among seropositive pregnant women.

Study design: This was a prospective cohort study of women who were cytomegalovirus seropositive at a single tertiary care hospital between September 1, 2018, and September 1, 2020. The participants were eligible if positive for cytomegalovirus immunoglobulin G during the first trimester of pregnancy. Urine samples were planned to be collected from each trimester. DNA was isolated in urine samples to detect and quantitate cytomegalovirus immediate-early 1 gene. Participants were classified as "ever shedder" if cytomegalovirus was detected in any urine sample and "never shedder" if cytomegalovirus was never detected. Patient demographics and characteristics were compared between groups. Stochastic search variable selection (with a posterior probability of inclusion of >0.5) was used to identify predictors of cytomegalovirus shedding at any time point. Forward selection modeling was used as a sensitivity check for independent risks.

Results: A total of 240 participants who were cytomegalovirus immunoglobulin G seropositive were enrolled, with 567 urine samples analyzed across gestation. Fifty-eight participants (24.2%) were "never shedders", and 182 participants (75.8%) were "ever shedders." The characteristics and demographics were similar between cohorts. With stochastic search variable selection, nulliparity was the only variable selected (odds ratio, 1.82; 95% credible interval, 1.00-4.09; Bayes factor, 2.22). Furthermore, nulliparity was selected with standard logistic regression, with an odds ratio and 95% confidence interval of 1.89 (1.00-3.58). Sociodemographic characteristics, such as age, race, education level, occupation, children at home, children in daycare, housing type, insurance type, income, and concurrent infections, were not associated with shedding. The only positive neonatal sample (0.42%) was detected from a participant who had cytomegalovirus detected in all 3 time points.

Conclusion: Approximately 75% of women who were positive for cytomegalovirus immunoglobulin G shed virus at some point during gestation. Nulliparity was the only variable selected that was associated with shedding.

Keywords: antiviral agents; congenital cytomegalovirus; congenital viral infection; cytomegalovirus; cytomegalovirus immunoglobulin G; fetal infection; secondary maternal cytomegalovirus infection; seroconversion.