Children Born at Short and Long Interpregnancy Intervals Have a High Risk of Autism

A team of researchers has found that children who are born at short and long interpregnancy intervals are at a higher risk of being diagnosed with the pervasive developmental disorder - autism.

Autism is a complex developmental disability that is a result of a neurological disorder that has a detrimental effect on the normal brain function, affecting the development of the person's communication and social interaction skills. According to the U.S. Centers for Diseases Control and Prevention, one in 68 births is diagnosed with autism.

In the latest study, researchers at the Columbia University used the data retrieved from the Finnish Prenatal Study of Autism  (FIPS-A) and found that children who were born either less than a year or more than 5 years of the birth of the previous sibling, face a higher risk of being diagnosed with autism as compared to children who were conceived following an interval of 2-5 years.

Keely Cheslack-Postava - PhD., of Columbia University - said, "It was intriguing to see that the risk of ASD diagnosis was higher in both closely and distantly spaced pregnancies. It is important to realize that we can't say from this study that spacing of pregnancies per se is a cause of ASD-this is most likely a proxy of other factors that are more directly related to the chance of the child's developing ASD.  In other words, the importance of this finding lies in the clues that it can provide in terms of understanding how the prenatal environment is related to outcomes after birth."

The FIPS-A included more than 7371 children who were born between 1987 and 2005 in Finland. It was estimated that close to a third of the children were diagnosed with autism. In order to compare the spacing of pregnancies between children who were diagnosed with autism and who were not, the researchers used data from several national registries.

Those children who were conceived in less than 12 months after the birth of a sibling had nearly one and a half times higher risk of developing autism than those who were conceived following an interval of 24-59 months. Children who were born after an interval of 60-120 months were 30 percent more likely to be diagnosed with autism.  The risk was 40 percent higher among those who were born after interval of more than 120 months.

During the analysis, the researchers considered certain factors like parents' age, prior number of children, and parental history of psychiatric disorders.

 The senior author of the study, Dr. Alan Brown, of Columbia University, said, "This study provides further evidence that environmental factors occurring during or near the prenatal period play a role in autism, a serious and disabling condition that afflicts millions of individuals and that is increasing in prevalence.  This work also exemplifies the importance of large samples of pregnancies with data acquired during pregnancy and their linkage to comprehensive, national databases of reproductive factors and psychiatric diagnoses."

The study was documented in the Journal of the American Academy of Child and Adolescent Psychiatry.