Cerebral palsy, caused by brain damage before or during birth, is 12 times more likely to strike twins than babies born singly, a study said Wednesday.
Doctors said they reached the conclusion from a study of 2,985 children in twin pregnancies born in California from 1983 to 1985."Twin pregnancies produced a child with cerebral palsy 12 times more often than singleton pregnancies," said the report from the California Department of Health Services, the National Institute of Neurological Disorders and Stroke and the University of California in San Francisco.
The researchers said twins are more likely to have low or very low birth weights, a risk factor for the damage that leads to cerebral palsy.
In addition, even twins with normal birth weights run a higher risk of brain damage than single-birth children, they said.
The study also found that there was no difference in the cerebral palsy risk between same-sex twins and fraternal twins. But in cases where one of the twins survived the fetal death of a brother or sister, the risk of cerebral palsy was 108 time higher than in single births.
The study said there has been an "explosive increase" in multiple births in the United States, due to fertility drugs and to an increasing number of older women bearing children.
As a result more cerebral palsy victims are likely to enter the population, it said.
The study was published in this month's issue of "Pediatrics," the journal of the American Academy of Pediatrics.