Pregnant women more attractive to mosquitoes due to higher fungal alcohol levels, study finds

A new study from the Swedish University of Agricultural Sciences (SLU) has found that pregnant women are significantly more attractive to mosquitoes because they emit higher levels of octenol, a compound also known as fungal alcohol.

Researchers determined that pregnant women release more octenol—a byproduct of broken-down sebum found in all mammals—making them prime targets for mosquitoes, according to the study published in the journal iScience. “All of us are differently attractive to mosquitoes, but pregnant women are definitely among the most attractive,” said Rickard Ignell, the professor leading the research.

The findings build on earlier malaria mosquito studies but focused on the yellow fever mosquito, testing the attractiveness of 42 women through collected scent samples. While speculation persists about the role of menstrual cycles, Ignell confirmed that pregnancy clearly increases mosquito attraction.

Despite this, Sweden’s 2026 mosquito season is expected to be milder overall due to an unusually snow-poor winter and dry spring, reducing early-season mosquito populations, said Anders Lindström, a researcher at the National Veterinary Institute. “This usually means fewer mosquitoes, though local variations can occur,” he noted.

However, species hatching in permanent water sources like ponds and lakes remain unaffected by drought, and later summer floods could still trigger outbreaks of aggressive floodwater mosquitoes. Octenol, already used in commercial mosquito traps, may explain why pregnant women face higher exposure when mosquitoes are present.

Researchers plan further studies tracking women through different stages of pregnancy and menstruation to deepen their findings.