Dengue infection in pregnancy: prevalence, vertical transmission, and pregnancy outcome.

Objective: To estimate prevalence rate of recent dengue infection in parturients, as well as the vertical transmission rate, and to compare pregnancy outcomes among infected women.
Method: A prospective cohort study was performed. Maternal and paired umbilical cord bloods were taken at delivery. A brief questionnaire on febrile illness and dengue in pregnancy was completed by participants. The samples were sent to a World Health Organization Collaborating Center for Arbovirus Reference and Research. Maternal sera were tested with a dengue-specific immunoglobulin M (IgM) capture test. The paired umbilical cord serum was tested to determine when the maternal sample was positive. Dengue reverse transcriptase polymerase chain reaction (PCR) was performed on all dengue IgM-positive sera. Pregnancy outcome was extracted from delivery records.
Results: A total of 2,958 parturients were enrolled, and 2,531 paired maternal-umbilical cord blood samples were available for testing. Dengue-specific IgM was positive in 63 of 2,531 (2.5%, 95% confidence interval [CI] 1.9-3.2%) maternal samples. Only 1 of 64 (1.6%, 95% CI 0.0-9.5%) of the paired umbilical cord sera was IgM-positive. All reverse transcriptase PCR tests were negative. Fifty-six of 63 (88.9%) of dengue IgM-positive women did not report a febrile illness in pregnancy. Apart from a higher mean age in dengue IgM-positive women of 30.6+/-5.2 compared with 29.2+/-4.9 years (P=.025) compared with dengue IgM-negative women, all other characteristics were similar. Rates of preterm birth, mode of delivery, postpartum hemorrhage, low birth weight, and neonatal outcomes were not different.
Conclusion: Recent dengue infection was demonstrated in 2.5% of parturients, with a vertical transmission rate of 1.6%. Pregnancy outcome of recently infected women was not different.
Level of Evidence: II.