Research has shown that significant stress during pregnancy may affect foetal growth and development, but less is known about whether this has long-term effects on children's cognitive functioning.
The new study assessed intellectual and language development in 89 children who were five year old whose mothers were pregnant during an ice storm in Quebec, Canada that left several million without power for as long as six weeks.
The researchers found that language development and verbal IQ tended to be lower in children whose mothers had faced the most stress during the storm - living more days without power, being forced to stay in a shelter, or losing income, for instance.
All of the children were within the normal range for intelligence and language development, note the researchers, led by Dr. David P. Laplante of Douglas Hospital Research Centre in Canada.
However, they say, the findings suggest that prenatal stress might have lingering effects on children's brain structures - particularly those involved in language and verbal abilities.
Laplante and his colleagues report their findings in the Journal of American Academy of Child and Adolescent Psychiatry.
It's not clear exactly why serious prenatal stress would affect children's intellectual development, according to the researchers. But the link held even when they factored in parents' education, income and occupation, which themselves were independently related to children's test scores.
"We suspect," Laplante and his colleagues write, "exposure to high levels of objective (prenatal stress) may have altered foetal neurodevelopment, thereby influencing the expression of the children's neurobehavioral abilities in early childhood."
They add that more severe natural disasters, like Hurricane Katrina or the 2004 Asian tsunami, likely had greater effects on pregnant women, and, potentially, their children.
However, the researchers conclude, more studies are needed to confirm that such prenatal stress can in fact "program" foetal brain development.