Women who develop infections while pregnant have an increased risk of bearing a child with cerebral palsy.
Danish researchers scoured the birth-related medical records of almost 500 children - both with and without the disorder - born during the 1980s.
They found mothers who had suffered common vaginal conditions, such a urinary tract infection, during pregnancy were three to six times more likely to have a child with cerebral palsy.
The research will be officially released at a global cerebral palsy summit to be staged in Sydney from Wednesday.
Commenting on the findings, Cerebral Palsy Australia president Diana Heggie said it offered a rare insight into the cause of the most common form of childhood disability.
"To date, research relating to the cause of cerebral palsy has provided very little conclusive evidence," Ms Heggie said.
"These findings linking maternal infections during pregnancy to the development of some causes of cerebral palsy is paramount, to both those working in the field and expecting parents."
Ms Heggie said the findings offered doctors and parents an "identifiable risk factor" to address during pregnancy and "progress towards identifying causes helps us to better understand ways to reduce the incidence of cerebral palsy".
New research into a second risk factor will also be detailed at the summit.
Researchers, again in Denmark, also found higher rates of cerebral palsy among children born as a result of in-vitro fertilisation (IVF) and other forms of assisted conception.
Babies born prematurely, or as part of a multiple birth, are known to suffer higher rates of the disorder and these are more common in IVF births than normal births.
The Third International Cerebral Palsy Conference - the largest of its kind in the world - will be staged at the Sydney Convention Centre over four days from Wednesday.
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