Premature birth can lead to a host of health problems, with serious disorders like cerebral palsy, mental retardation, developmental delays, and behavioral problems more prevalent among those born before the 37th week of pregnancy. A new study included in this month's issue of Pediatrics points toward another diagnosis that may be more common in premature babies. Researchers from Children's Hospital Boston and Harvard Medical School have demonstrated that children born very prematurely may also be more likely to have autism.
The study's 91 subjects were born an average of 10 weeks early and weighed in at less than 3.3 pounds at birth. While in the neonatal intensive care unit, they received MRI scans, and the researchers also collected data on their demographic information, health, and short-term outcomes. At around 22 months, the subjects were evaluated a second time, and the researchers used a number of assessment tools to gauge each child's chances of being diagnosed with autism. To screen for autistic behavior and communication deficits, they used the Modified Checklist for Autism in Toddlers (M-CHAT). Additionally, they used two other assessments to examine the children's internalizing (anxiety, social withdrawal) or externalizing (aggression) behavior and evaluate their communication, social, and motor skills. Because developmental delays are common in premature babies and do not necessarily indicate a long-term problem, they controlled for language and motor control delays associated with premature birth.
Overall, the researchers identified 23 children, or 26 percent of the sample, who scored high on measures of autistic behavior. These children were also more likely to display internalizing behavior and deficits in socialization and communication. These results are telling, but they are not free from limitations. The researchers stress that the M-CHAT and other assessment tools used in this study are not used to diagnose autism in children. Rather, they identify children who are most at risk and should receive further evaluation. While the researchers cannot say if prematurity plays a direct role in autism, they identified several factors associated with premature birth that may increase a child's chances of receiving an autism diagnosis. Those who were most premature and who weighed the least at birth were more likely to display autistic behavior, and, as was expected, boys were also at an increased risk. Additionally, the researchers found that autistic behavior was more common in children whose mothers had an infection prior to birth, whose mothers hemorrhaged during labor or delivery, who were born with an illness, and who had an abnormal MRI.
This study raises new questions about the relationship between autism and premature birth, and further investigation might clarify whether this association is a lasting one or one that will dissipate as the children age and mature. The researchers plan to continue monitoring their subjects, and knowing how many are subsequently diagnosed with autism will allow for a better understanding of this study's findings. Continued research with larger sample sizes could also help explain why this relationship occurred and what we can do to aid the families affected by it. Early screening for premature babies may be an important step, allowing physicians to identify those most at risk and ensure they have access to the interventions that can improve their long-term outcomes.
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