Jaundice May Increase Risk of Autism
More than half of term newborns have jaundice, and now a new study suggests that these infants are 67 percent more likely to develop autism. Although jaundice typically disappears within the first week of life, a persistent case is known to cause serious health problems.
A link between jaundice and autism needs further study
Jaundice occurs in 60 percent of term infants. Newborn jaundice is characterized by high levels of bilirubin, a yellow pigment that the body produces during the normal recycling of old red blood cells. The liver is responsible for processing bilirubin so it can be eliminated through stool.
Before a child is born, the placenta removes bilirubin from the infant and the mother’s liver processes it, but immediately after birth, an infant’s own liver is supposed to take over. Jaundice usually appears between day 2 and 3 after birth and clears up by two weeks.
A common form of newborn jaundice is breast milk jaundice. Breast milk may contain a substance that increases the reuse of bilirubin, and so jaundice can appear in healthy breastfed babies and last at low levels for about a month.
Researchers involved with the new study, which evaluated nearly 734,000 infants born in Denmark between 1994 and 2004, discovered that the increased risk of autism associated with jaundice was greatest among women who had previous children or if the child was born between October and March. This latter result may be associated with exposure to sunlight, which has an impact on jaundice, or the presence of infections, which may be higher during the winter months.
Jaundice can also indicate a serious underlying problem that is interfering with the body’s ability to process and remove bilirubin, including cystic fibrosis, Gaucher’s disease, infections, congenital syphilis, congenital rubella, congenital hypothyroidism, and neonatal hepatitis, among others. If jaundice is left untreated, very high levels of bilirubin can damage the brain, resulting in cerebral palsy, deafness, and kernicterus.
Researchers with the Denmark study note that the difference in risk of autism in firstborn versus subsequent children could be associated with differing levels of antibodies in mothers or it could reflect varying levels of access to health care in the immediate days following delivery. In any case, the finding that jaundice in newborns may be associated with an increased risk of autism deserves further investigation.
March of Dimes
MSNBC News, Oct. 11, 2010
National Institutes of Health