My theme this week is girls with autism. Yesterday I wrote about a genetic study on Retts Syndrome which affects only girls. Today I'm writing about new research conducted by scientists at the National Center on Birth Defects and Developmental Disabilities at the CDC.
According to an article about the study, recently published in Pediatrics, their study reveals that there is a connection between baby girls with low birth weight and autism. The connection wasn't expected, especially considering that autism is more common in boys with one girl to every four or five boys being diagnosed.
Diana Schendal, lead scientist at the Center and her colleague Tanya Karapurkar Bhasin looked at the records of 565 children born between 1986 and 1993. The scientists considered whether the children were born early, small, or both, and whether they had autism and other developmental problems. Then they divided the children with autism into three groups: those who had autism but no other developmental disabilities, those with autism who also had an intellectual disability, and those with autism and more than one other developmental disability
Schendel and Bhasin found that girls had a threefold or higher risk of autism if they were born with a low birth weight (less than 5.5 pounds) in comparison to boys, who had less than a twofold risk of autism if they were born with a low birth weight. The scientists also found low birth weight and early preterm birth (less than 33 weeks' gestation) affected groups of children differently, depending on whether they had autism alone or autism and other developmental disabilities. Although preterm birth earlier than 33 weeks was not statistically linked to autism for boys, there was a significant fivefold increased risk seen for girls with autism.
Here is an excerpt from the original article:
"There may be a lot of variation in the endpoint we call autism," Schendel tells WebMD. The study result, she says, "really is highlighting that we aren't looking for one cause of autism ." The study builds on previous research, some of which has also found a link between low birth weight and autism."What is new in this study is the in-depth look at the gender effect," she says.
Schendel can't explain why the low-birth-weight girls were found to have a greater risk than the low-birth-weight boys. Both low birth weight and preterm birth are markers, she says, that something may have gone wrong during the pregnancy. The poor fetal growth resulting in low birth weight may be associated with developmental problems. Or, on the other hand, low birth weight may be a marker of a fetus that's already adversely affected neurologically, she says."We don't know if it's the low birth weight ... causing brain damage, or whether the brain damage has occurred and low birth weight is the consequence," she tells WebMD."