A prospective matched study on symptomatic dengue in pregnancy.

Dengue fever is an increasing problem worldwide, but consequences during pregnancy remain unclear. Much of the available literature suffers from methodological biases that compromise the validity of clinical recommendations. We conducted a matched cohort study during an epidemic in French Guiana to compare events and pregnancy outcomes between two paired groups of pregnant women: women having presented with symptomatic dengue during pregnancy (n = 73) and women having had neither fever nor dengue during pregnancy (n = 219). Women in each arm were matched by place of follow up, gestation weeks at inclusion, and place of residence. Dengue infection was considered to be confirmed if viral RNA, N S1 antigen, the seroconversion of IgM antibodies or the presence of IgM was detected in collected samples. According to the 2009 WHO classification, 27% of the women with symptomatic dengue had at least one clinical or biological warning sign. These complications occurred after the 28th week of gestation in 55% of cases. The medical history, socioeconomic status and demographic characteristics were included in multivariate analysis. Exposure to dengue during pregnancy was not significantly associated with prematurity, small for gestational age infants, hypertension or emergency caesarian section. Maternal dengue with warning signs was a risk factor for peripartum hemorrhage with adjusted relative risk = 8.6(95% CI = 1.2-62). There was a near significant association between dengue and in utero death (p = 0.09). This prospective comparative study underlined the importance of taking into account potential confounders between exposure to dengue and the occurrence of obstetrical events. It also confirms the need for increased vigilance for pregnant women with dengue, particularly for women who present with severe dengue.

Estimating the Risk of Vertical Transmission of Dengue: A Prospective Study.

The incidence of dengue worldwide is increasing rapidly. A better understanding of dengue transmission may help improve interventions against this major public health problem. The virus is mostly transmitted by vectors. There are, however, other modes of transmission, notably mother-to-child transmission or vertical transmission. We studied a prospective cohort of 54 women who had dengue while pregnant during the 2012-2013 epidemic in French Guiana to estimate the mother-to-child transmission rate and assess the clinical and biological presentation of neonatal dengue. The rate of vertical transmission was between 18.5% (95% confidence interval [CI]: 9.25-31.4) and 22.7% (95% CI: 11.5-37.8), depending on the calculation method used. Mother-to-child transmission occurred both in early and late pregnancy. There were 52 births, including three newborns who presented neonatal dengue with warning signs requiring platelet transfusion. This quantification of the mother-to-child transmission of dengue highlights three points: first, vertical transmission of dengue is not negligible; second, it is more frequent when maternal dengue occurs late during pregnancy near delivery; and third, reliable diagnostic tests must be used to allow the diagnosis of vertical transmission. Our findings indicate that if there is a known history of maternal dengue during pregnancy, or if there is fever during the 15 days before term, cord blood and placenta should be sampled after delivery and tested for the virus, and the newborn should be closely monitored during the postpartum period.