Close births among siblings can increase risk of autism in second child

By Staff Writer

A new study reveals that mothers who give birth to multiple children within a two-year span are increasing the risk of the second baby having autism.

The report, which will appear in the February issue of Pediatrics, studied the association of siblings that are born close together and the development of autism. Researchers from Columbia University examined the birth record for approximately 660,000 second-born children between 1992 and 2002.

They found that babies who were conceived within a year of their sibling's birth were nearly three times as likely to have the developmental disorder, compared to children who were conceived more than three years apart. Babies that were conceived between 12 and 23 months were about twice as likely to develop autism, while those conceived between 24 and 35 months were 26 percent more likely.

While the reasons why closely spaced pregnancies increase the risk of autism is not known, some experts speculate that the mother's body does not have enough time to recover from the previous pregnancy. The study's researchers said that the first pregnancy may deplete critical nutrients, such as folate and iron. Furthermore, they suggested that the mother's body may be under greater stress during the second pregnancy.

According to the Centers for Disease Control and Prevention, an average of one in 110 children in the U.S. have autism.