Findings from a 10-year investigation could shed some light on what causes children to develop psychological disorders such as autism.
Exposure to jaundice as a newborn is associated with an increased risk of being diagnosed with autism or another psychological development disorder, according to findings from a study that tracked all Danish children born during a 10-year period.
The study, published in the November issue of Pediatrics, found that full-term infants born between 1994 and 2004 who had jaundice were 67% more likely to develop autism. Neonatal jaundice—a condition that usually results from elevated bilirubin production—presents in 60% of term infants. For most infants, it resolves within the first week of life; however, prolonged exposure to high bilirubin levels is neurotoxic and can cause lifelong developmental problems.
Rikke Damkjaer Maimburg, MPH, PhD, of Aarhus University in Aarhus, Denmark, led a population-based study to examine the association between neonatal jaundice and disorders of psychological development, and to assess whether gestational age, parity, and season of birth influence the association. Data was collected from four national registries, and survival analysis was used to calculate hazard ratios.
Maimburg and colleagues found that “exposure to jaundice in neonates was associated with increased risk of disorders of psychological development for children born at term. The excess risk of developing a disorder in the spectrum of psychological development disorders after exposure to jaundice as a neonate was between 56% and 88%.”
In analyzing the data, they concluded that the risk of autism was higher if the mother had given birth to previous children, or if the child was born between October and March; conversely, the risk for autism disappeared if the child was a firstborn child or was born between April and September. The authors suggested that the seasonal difference may be due to different levels of exposure to daylight, which has an effect on jaundice, or may be due to infections.
The difference in risk in firstborn versus subsequent children could be attributed to different levels of antibodies in women who have had multiple pregnancies, or it could reflect different levels of access to health care in the first days after delivery, they wrote. In Denmark, women with healthy term newborns who have already given birth to children are discharged soon after delivery, whereas women having their first child remain in the hospital for three to four days. Therefore, jaundice may be diagnosed while the infant is still in the hospital.
The authors did not that the study did not explore the severity of jaundice.
In light of these findings, do you think physicians will more closely observe infants with jaundice for early signs of autism? Or is more research needed to confirm the link?