Dengue is a viral infection transmitted through the bite of several species of Aedes mosquito, which threatens the health of approximately half of the world's population. It is more common in tropical and subtropical climates but is gradually spreading to southern Europe and US states because of climate change. Although many cases are asymptomatic, the virus can trigger a mild to severe flu-like illness, and occasionally death, but there had been little strong evidence linking it to worse birth outcomes following pregnancy until now.

Researchers at the Universities of Surrey and Birmingham in the UK analysed health records for women and children living in the highly populated south-eastern Brazilian state of Minas Gerais between 2011 and 2017, linking statistics on births, deaths, hospitalisations and dengue infections over time.