In a 2005 study, rat pups were deprived of oxygen for as long as ten to twelve minutes during birth (by increasing the level of nitrogen in the air). As they grew older, the oxygen-deprived rats showed autistic-type symptoms, including delayed or disrupted reactions to sound. The study suggests that there may be a correlation between oxygen deprivation at birth and autism later in childhood.
I became aware of this study after reading through a fascinating thread on an ASD message board on Circle of Moms. Dozens of women were discussing the difficult births of their autistic children - umbilical cord strangulation, unusually quick deliveries, emergency c-sections - that all included oxygen deprivation. Obviously this is not a scientific sample, and I'm sure you could find lots of autistic kids who were not deprived of oxygen (and suffocating newborns who never developed any special needs). But I'm really into the idea that there may be some sort of connection between poor air supply and early brain development.
Are we seeing more diagnoses of ASD these days because doctors are better able to keep struggling newborns alive than they were 20 years ago? Could it have something to do with the modern medical practice of clamping off the umbilical cord too soon after birth? Apparently, although blood continues to pulse through the cord for about 5 minutes after birth, doctors often clamp it off after 30 seconds to a minute, thereby cutting off the newborn's oxygen supply before his/her lungs are 100% functional. This can lead to birth injuries such as cerebral pasly, retardation, learning disabilities, and autism.
So, in the interest of totally non-scientific inquiry, I pose this question to you, Dear Reader: was your child somehow deprived of oxygen at birth, and do you consider your child neurotypical or somehow challenged? I'll start: Ryan wasn't breathing at birth, and has PDD.
An addendum: I wrote a note to the researchers on the Interactive Autism Network project, and Dr. Connie Anderson wrote the following in response:
"So far, various researchers have found some slight associations between autism and various pregnancy and birth related factors. In a recent article on the epidemiology of autism, Newschaffer et al wrote, 'Uterine bleeding, Cesarean section, low birthweight, preterm delivery, and low Apgar scores are among the few factors that have been more consistently associated with autism... Methodologic issues continue to challenge the synthesis and interpretation of this body of evidence. The underlying cause of a measured obstetric factor or set of factors is rarely known, nor is the temporal relationship between the obstetric event and the actual biological onset of autism.' (The Epidemiology of Autism Spectrum Disorders, Annual Review of Public Health 2007, Vol 28, pg 244)
"In brief, there have so far been some associations found, but little is still little understanding of whether they are cause or effect or how they even relate to autism's onset."