OBJECTIVE: to determine whether dengue epidemics are associated with an increase in adverse obstetrical outcomes. METHODS: semi-ecological study combining individual data on obstetrical events from the perinatal registry and aggregated exposure data from the epidemiologic surveillance of dengue in Cayenne, French Guiana between 2004 and 2007. RESULTS: after adjustment for individual risk factors, analysis showed that an epidemic level of dengue transmission during the first trimester was associated with an increased risk of post-partum haemorrhage and preterm birth. The associated risks seemed to depend on the epidemic level. CONCLUSIONS: despite its limitations, this study suggests that dengue in the first trimester may be related to preterm birth and to post-partum bleeding, thus leading to specific hypotheses that should be tested in prospective studies. (R.A.)