Small babies, born weighing less than 4lbs may be more at risk of developing autism compared to babies of normal weight. This is the finding of a study that found that a disproportionate number of autism cases were diagnosed amongst babies of low birth-weight (some five percent of small babies had an autistic spectrum disorder – compared to 0.9 percent of all babies of all birth-weights).
However, the study compared the low birth-weight babies who were the subjects of the study with general population estimates rather than against a specific group of normal birth-weight babies. Since the low birth-weight babies were given specific tasks and assessments that babies in the general population wouldn’t have undergone, an obvious criticism of the report is that it’s hard to know if these children would be diagnosed as autistic if they weren’t part of the study. Some of the children studied, for instance, did not have an official diagnosis of autism from a doctor, but their scores on the tests carried out suggested that they were on the autistic spectrum.
A more robust study with a proper control group is needed. However, it is an interesting finding and worthy of further discussion. How would birth-weight affect a child’s risk of developing autism, if that were indeed the case?
Autism and autistic spectrum disorders have three broad types of symptoms: communication problems, social interaction problems, and unusual thought patterns and physical behaviour. These are skills usually controlled by the left side of the brain, so perhaps a child born at low birth-weight hasn’t developed the links between the two halves of the brain, or perhaps the left brain is insufficiently developed. This is all speculation, of course, since the true causes of autism are still under investigation.
Low birth-weight is known to cause some cognitive and physical problems. But as for autism: Professor Dorothy Bishop, Developmental Neuropyschologist at the University of Oxford says, ‘The association looks real, but nevertheless, most low birthweight children don’t have autism, and most children with autism don’t have low birth weight.’