Twelve to 13 percent of autism cases stem from pregnancy issues that result in prematurity, low birth weight or Caesarian section, according to a new report by the Centers for Disease Control and Prevention (CDC). The findings support the results of earlier studies on pregnancy risk factors for autism. They are published online in the Annals of Epidemiology.
In their report, the CDC researchers emphasize that their findings do not indicate that C-sections, low birth weight or prematurity cause autism. Rather they are all likely linked to underlying pregnancy complications. Their report did not distinguish emergency C-sections from elective ones.
In their study, the investigators tapped into eight sites in the CDC’s Autism and Developmental Disabilities Monitoring (ADDM) Network. This allowed them to look at the birth records of 2,042 children with autism. They compared each ausim case with the birth records of 20 children without autism. The cases were matched by birth year, gender, county, race-ethnicity, age and education.
“Though the ADDM network is not nationally representative, it’s the most comprehensive autism surveillance system we have in the US,” comments epidemiologist Michael Rosanoff, Autism Speaks associate director for public health research. “Certainly, these findings can point us in the right direction for more extensive and targeted research on pregnancy risk factors.”
In particular, the results suggest the need for greater understanding of the underlying pregnancy issues that lead to prematurity, low birth weight and C-section.
“This study reinforces what we know about the relationship of preterm birth, small size for gestational age and C-section and increased risk for neurodevelopmental problems in general,” concurs developmental pediatrician Paul Wang, Autism Speaks senior vice president for medical research. “As the authors conclude, these risk factors really reflect deeper issues during pregnancy. The bottom line is that we must do our best to support women when they are pregnant.”
In related news, the American College of Obstetricians and Gynecologists just issued new guidelines generally urging doctors away from elective C-sections. In particular, the guidelines discourage caesarians for first-time mothers who are simply wearying of labor. They note that long first labors are normal and that vaginal delivery generally benefits both mother and child. By contrast, emergency C-sections are generally performed because mother or child are in danger.
Please also see these pregnancy-related resources on the Autism Speaks website:
Also see the CDC’s Guidance for Preventing Birth Defects