Zika is no longer the only arbovirose infection to be considered lethal to a developing baby. A scientific study has found that dengue can also pose a risk to the life of the fetus. Having dengue during pregnancy almost doubles the likelihood of a baby being born dead or dying during childbirth, while severe dengue fever would increase five times the chances of a stillbirth – a name given to the death of the fetus above 500g inside the uterus or during delivery .
The finding, published in the September issue of The Lancet, was obtained from the analysis of records of Brazilian information systems. To reach such results, researchers cross-checked the data of more than 162,000 stillbirths and 1.5 million live births, of which 275 stillbirths and 1,507 live births had been exposed to dengue.
This is the first large-scale study to demonstrate the association. Only one previous study, with a small sample from a hospital, indicated the relationship between infection and stillbirth.
The paper, titled “Symptomatic dengue infection during pregnancy and the risk of stillbirth in Brazil, 2016-12: matched case-control study”, counted on the authorship of the researchers of the Center of Data Integration and Knowledge for Health (Cidacs / IGM / Fiocruz), Enny Paixão, Mauricio Barreto, Maria Glória Teixeira and Laura Rodrigues, in partnership with researchers from the Institute of Collective Health of the Federal University of Bahia (ISC / UFBA), University of São Paulo (USP) and the London School of Hygiene & Tropical Medicine, in the United Kingdom.
The study was conducted with data obtained between December 2012 and January 2016 from Sinasc (Birth Information System), SIM (Mortality Information System) and Sinan (National System of Notifiable Diseases).
The analysis indicated that the risk of stillbirths among all births recorded in the period was 11 per 1,000 live births. When considering only the sample of mothers infected with dengue, the incidence rate was 15 per 1,000. When considered the severity of the disease, severe dengue increases the risk of stillbirth five times, about three times more than common dengue. However, the relationship can still be considered rare and can only be pointed out due to the large volume of records analyzed.
The mechanisms by which dengue would cause the birth of stillbirths is unknown, but the researchers point out three hypotheses to explain the phenomenon: the symptoms of dengue would directly affect the fetus; dengue would cause changes in the placenta; or the virus itself would have a direct effect on the baby in training.
Although since the 1980s Brazil has experienced systematic epidemics of dengue, the disease was considered lethal only when it reached its hemorrhagic form, which worsened the picture of the infected and could lead to death. However, with the congenital anomaly epidemic associated with Zika in 2015, scientific research turned to the effects of viral infections during pregnancy.
By 2015, about 2.6 million babies were considered stillbirths worldwide. The estimate is that viral infections, in general, account for about 14% of all fetal deaths. Some infections have strong scientific evidence of association with stillbirths: Syphilis, Toxoplasmosis, Cytomegalovirus and Parvovirus B19.