Seroconversion for Cytomegalovirus in a Canadian Cohort of Pregnant Women
Methods: This study used serum samples and questionnaire data collected as part of the 3D Pregnancy and Birth Cohort Study (Quebec, Canada, 2010-2013) designed to investigate the effect of a range of prenatal factors on birth outcomes. Consent allowed for subsequent use of data and biobanked biological specimens. Women who had serum banked from both the end of the first trimester and the third trimester were included. Serum CMV IgG antibodies were determined. Women who were seronegative in early pregnancy had their late serum tested to determine conversion rates. Associations between independent variables and seroprevalence were assessed using logistic regression, and associations with seroconversions, by Poisson regression.
Results: Of 1938 subjects tested in early pregnancy, 1156 (59.6%) were seronegative for CMV, and 35 seroconverted (3.0%) by the end of pregnancy. The seroconversion rate was 2.0 (95% CI 1.4-2.8) per 10, 000 person-days at risk or 5.7 (95% CI 4.0-7.9) per 100 pregnancies assuming a 280-day gestation. Maternal factors independently associated with seropositivity were working as a daycare educator or a kindergarten teacher (OR= 5.0, 95% CI 1.8-13.9), first language other than French or English (OR = 4.0, 95% CI 2.7-5.5), being born outside Canada or USA (OR = 4.0, 95% CI 2.9-5.3), lower education (primary or secondary vs. university, OR = 2.6, 95% CI 1.8-3.7), and having had children (OR 1.3, 95% CI 1.1-1.7). Among initially seronegative pregnant women, those born outside Canada or USA were at higher risk of seroconversion (RR = 3.1, 95% CI 1.3-7.3).
Conclusion: Nearly 60% of pregnant women in this cohort were susceptible to CMV in early pregnancy. Overall seroconversion rates approaching 6% are of concern with seronegative women born outside Canada and the USA being at higher risk; targeted interventions may be needed in this group. Further data are needed on the effectiveness of public health prevention strategies.
C. Rousseau, None
T. W. Gyorkos, None
W. D. Fraser, None