Despite concerns that a mother's infections during pregnancy may raise her baby's risk of cerebral palsy, common colds and stomach flu were not tied to the birth defect in a new study.
Other more serious infections, and factors like a woman's history of miscarriage or family history of cerebral palsy, were associated with increased risk to babies, Dr. Michael E. O'Callaghan of the University of Adelaide, Australia, one of the study authors told Reuters Health. "There's an increased chance but it's still low."
In particular, severe maternal infections in the second half of pregnancy were linked to higher risk for babies. So were pre-term birth, growth restrictions inside the uterus and being a twin or part of a larger set of multiples.
Cerebral palsy describes a number of disorders of the developing brain that affect body movement, posture and balance. It occurs during fetal development, or during or right after birth, and its cause is unknown.
Published in Obstetrics and Gynecology, the study by O'Callaghan and his colleagues looked at 587 people with cerebral palsy and 1,154 without the disorder.
The researchers found that maternal infections like chicken pox and cytomegalovirus -- an infection that causes serious symptoms in newborns -- were significantly associated with cerebral palsy, especially when they happened in the second half of pregnancy. Those types of infections occurred during pregnancy in the mothers of 41 percent of people with cerebral palsy compared to 31 percent who didn't have the condition.
When researchers looked at mothers' upper respiratory and gastrointestinal infections, however, they found no significant difference between people with cerebral palsy and those without it. Upper respiratory infections occurred in the mothers of about 9.5 percent of people with cerebral palsy, for instance, and 8.5 percent of those without the condition.
Certain infections during pregnancy can affect the fetus, sometimes causing inflammation in or around the brain that could disrupt brain development.
"There's not a great deal of new information presented in this study but it is from a large population, which was then honed down to a small sample," said Dr. Bruce Young, professor of obstetrics and gynecology at the NYU Langone Medical Center, who was not involved in the research.
The study was based on records and maternal questionnaires, which Young points out may be biased.
"People sometimes don't remember," he said. "That's a big problem with this type of study."
The report does offer further evidence that premature deliveries, low birth weight, family history and infections are common risks associated with cerebral palsy, he noted.
"It's reassuring that there are factors associated with cerebral palsy that can be identified," said Young.
"Some of them, like premature births, can be addressed. We're coming up with new treatments to prevent pre-term births. That's optimistic for pregnant women."
Timing also played a role in the impact of more serious infections. Later in pregnancy, a mother's fever, or her infection with chicken pox virus, staphylococcus or streptococcus bacteria, and various wound or urinary tract infections, all raised babies' cerebral palsy risk by four to five times.
"I would not exclude infections during the first half of pregnancy based on this paper," Young told Reuters Health. "If a pregnant woman thinks she has an infection at anytime during the pregnancy, she should consult with her doctor promptly."
"If you have a fever, it should be lowered because that is the best way to protect your fetus as well as yourself," he said.