Researchers in the UK say that the common infections that affect mothers and babies may trigger certain types of childhood cancers.
They say they found that leukemia and brain tumors, which are the leading cancers in children, occurred in clusters which suggests that outbreaks of infections are a contributing cause of the disease.
Dr Richard McNally, of the University of Newcastle upon Tyne says they found that place of birth was particularly significant, which suggests that an infection in the mother while she is carrying her baby, or in a child's early years, could be a trigger factor for the cancer.
He says these could be minor, common illnesses such a cold, mild flu or a respiratory infection.
McNally and a team of researchers from England and Scotland, say the results of their study could improve understanding about how cancer develops and may lead to better prevention and treatment.
Cancer in children is relatively rare, but rates of the disease in children in Europe have increased over the past three decades.
However survival rates have improved with about a 75 percent, five-year survival rate in western Europe and 63 percent in eastern Europe.
Leukemia remains the most common childhood cancer, and accounts for nearly one-third of all cases and it seems most of the rise has been in children aged 1 to 4.
The researchers believe an infection in the womb or early in life could lead to cancer in young people who already carry mutant cells that would make them more vulnerable to the disease.
McNally says the virus could hit this mutant cell and cause a second mutation, prompting the onset of cancers like leukemia or brain tumors.
The researchers have based their findings on a statistical analysis of data from the Manchester Children's Tumour Register, which recorded all cases of childhood cancers diagnosed between January 1954 and December 1998.
They looked for unusual patterns of cancer linked to the time and place of children's birth and where they were living when diagnosed with cancer.
In some clusters they found 8 percent more cases of leukemia than would normally be expected and a 13 percent above-average incidence of the brain tumour astrocytoma.
Professor John Toy, of the charity Cancer Research UK, which funded the research, says the findings provide more clues to a link between viruses and some types of childhood cancer, but more evidence is needed to confirm this is so.
The findings are published in the European Journal of Cancer.