A new study has linked brain-damaging cerebral palsy in normal-weight newborns to certain infections in their mothers.
The findings suggest that many hard-to-explain cases of cerebral palsy may be caused by infection - not by oxygen deprivation during birth as scientists, families and malpractice lawyers have long believed.
The findings, published in the current Journal of the American Medical Association, also put cerebral palsy on a growing list of conditions, from multiple sclerosis to cancer, that have only recently been associated with infectious agents.
“This is really a shift in our thinking about the causes of cerebral palsy,” said co-author Judith Grether, an epidemiologist at the California Birth Defects Monitoring Program.
Experts hailed the new study, while stressing that it raises more questions than it answers about how to identify and treat infected women and infants. The researchers estimate that infections in the mother’s womb or urinary tract may account for at least 12 percent of cerebral palsy in normal-weight babies.
Cerebral palsy develops before, during or shortly after birth, impairing the brain’s control of muscles and movement. It may include retardation, seizures, blindness, and deafness. Each year, about 5,000 babies in this country are diagnosed with cerebral palsy.
It is clear that cerebral palsy can be caused by oxygen deprivation due to clear-cut problems such as premature separation of the placenta from the uterus, awkward birth position, or interference with blood flow in the umbilical cord. It is also clear that certain infections during pregnancy can trigger premature labor and birth, which increase the risk of birth defects including cerebral palsy.
However, more than half of babies born with cerebral palsy are normal weight. In many cases, their cerebral palsy cannot be explained, so it is blamed on oxygen deprivation.
The new study looked at such babies, identified from records of more than 155,000 births in the San Francisco area from 1983 through 1985. The researchers found 192 babies with cerebral palsy, then focused on 46 normal-weight (at least 5.5 pounds) infants with unexplained cerebral palsy.
Compared with a control group, these babies were nine times more likely to have been exposed to infection in their mother’s womb. The infections were all related to the uterus or urinary tract, except in a few cases involving sepsis, a life-threatening blood infection.
How could such an obvious link have been overlooked for so long?
For many reasons, the researchers and other experts say.
For one, these infections often have no symptoms during pregnancy, or in the babies after birth.
For another, many of the bacteria that can cause amniotic fluid infections are normally present in the vagina, making diagnosis difficult.
New research also suggests that the fetus may be harmed by its own immune response to infection in the womb - not by the infectious agent.
Subscribe to the Coronavirus newsletter
Get the day’s latest Coronavirus news delivered to your inbox by subscribing to our newsletter.