Second-born children conceived within one year of their older sibling’s birth are more likely to be diagnosed with autism than children born farther apart, new research suggests.
The study, published online today in the journal Pediatrics, is believed to be the first to indicate that closely spaced pregnancies might be an independent risk factor for autism in second-born children.
“We don’t yet know from this research what it is specifically about interpregnancy interval that matters, but this may provide an important clue about potentially modifiable risk factors for autism,” lead study author Keely Cheslack-Postava, of Columbia University, wrote in an e-mail.
The findings are based on birth records for more than 660,000 children born in California between 1992 and 2002.
Children with autistic older siblings were excluded from the study.
Researchers found that children conceived within a year of their sibling’s birth were three times more likely to be diagnosed with autism than those conceived after at least three years.
The trend held when researchers controlled for other known risk factors, such as parental age and premature birth.
The increase in autism risk may be related to depleted levels of folate, iron and other nutrients, as well as higher stress levels, in women who have had a recent pregnancy, Cheslack-Postava said. It could also be that autism symptoms are more easily recognized and diagnosed when there is an older sibling close in age to compare to.
Posted By: Siebra Muhammad
Monday, January 10th 2011 at 5:37PM
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