Study supports association between neonatal jaundice and autism

Findings of a study conducted in Denmark have added to accumulating evidence that exposure to neonatal jaundice is associated with autistic disorders and other disorders of psychological development. Gestational age, parity, and season of birth seem to play important roles in this association.

Data from 4 national registers on all 733,826 children born alive in Denmark between 1994 and 2004 showed that nearly 36,000 had a diagnosis of neonatal jaundice. In follow-up, 1,721 had a diagnosis in the spectrum of disorders of psychological development, including autism. Overall, children exposed to jaundice had an almost 90% greater risk of 1 of these diagnoses compared with unexposed children. The association held only for children born at term, however, with these neonates having a 56% to 88% greater risk of a disorder within the spectrum of psychological development disorders compared with children not exposed to jaundice as neonates. No increased risk was shown in premature babies with or without jaundice.

The excess risk of infantile autism was 67% and was higher if the child was born to a parous woman or was born between October and March; however, the increased risk for infantile autism disappeared if the child was born to a primiparous woman or was born between April and September. Investigators found similar risk patterns for the whole spectrum of autistic disorders (Maimburg RD, et al. Pediatrics. 2010;126[5]:872-878).

How is jaundice related to development of autism? Does jaundice constitute a second insult, coupled with genetic predisposition? How does season of birth relate? Does winter birth allow for more early infections, or is sun exposure a factor? The associations among autism, jaundice, birth order, and parity are fascinating, but they raise more questions than they answer. I look forward to the day when the pieces of this puzzle have been fit into place, revealing a full picture of the causes of autism and related disorders. -Michael Burke, MD