Many parents of children with autism may remember answering a long list of questions regarding their child’s early development during their autism evaluations: Was he/she premature? Were there any complications? Jaundice? Most often these questions are asked to gather information about other possible developmental factors that may explain the symptoms. Thus, this neonatal information is usually not directly relevant to the diagnostic criteria of autism, but it is used to rule out other disorders (such as a specific genetic syndrome). So I was intrigued when I read an article published this week in the journal Pediatrics that examined the association between jaundice and a number of developmental disorders, including autism.
The authors examined practically all children born in Denmark between 1994 and 2004 using the country’s Medical Birth Register. They examined several neonatal factors, including birth weight, parental age, gestational age, parental smoking, congenital malformations, and jaundice exposure. Developmental disorder diagnoses were obtained from the country health registers and included speech and language disorders, learning disabilities, mental retardation, and autism spectrum disorders.
Among full term babies, jaundice was associated with:
- A 56% increase in the risk for speech and language disorders
- A 56% increase in the risk for autism.
Among premature babies, jaundice was not associated with a higher risk for any disorder.
A few more interesting findings:
Jaundice was associated with a risk for autism only among kids born from October to March. For these kids, jaundice increased the risk for autism by 97%. In contrast, jaundice did not increase the risk for autism among kids born from April to September. Why? The authors suggested two possibilities. One, exposure to daylight is a standard treatment for jaundice. It is possible that kids born from October to March had significantly less light exposure (remember these kids are in Denmark, which has limited daylight during winter months). It is also possible that kids born during the winter are exposed to more viruses, infections and other conditions that may be responsible for the increased risk for autism.
Jaundice increased the risk for autism only among babies born to woman having their second+ child. For these kids, jaundice increased the risk for autism by 129%. In contrast, jaundice did not increase the risk for autism in kids who were the mother’s first child. Why? The authors also offered two possible explanations. First, it is possible that mothers having their second + child have accumulated more antibodies during pregnancy that could affect development. However, it is also possible that this is a byproduct of the Danish health system. The authors explained that mothers who had a successful first pregnancy are discharged from the hospital faster during their second + pregnancies (usually the same day of delivery). This limits access to care for second-born kids with jaundice during the first days of life. In contrast, babies who are the first-born receive more extensive care and are not discharged until the 3rd or 4th day after delivery. This could result in better management of jaundice and a reduction of the risk for autism.
But the question still remains, what is the mechanism by which jaundice increases the risk for autism among these full term babies?
And finally, just to put these results into context. Jaundice affects 80% of preterm babies and 60% of full term babies. This means that the vast majority of babies who are exposed to jaundice will not develop autism.
The reference: Maimburg, R., Bech, B., Vaeth, M., Moller-Madsen, B., & Olsen, J. (2010). Neonatal Jaundice, Autism, and Other Disorders of Psychological Development PEDIATRICS, 126 (5), 872-878 DOI: 10.1542/peds.2010-0052
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