In a July 9th, 2008 post, I added oxygen deprivation incurred at childbirth as another factor potentially contributing to an increased incidence in autism. As I noted in that blog:
“We have published compelling evidence that peri-natal anoxia meets all of the other criteria for adding to “noisy” brain processing. It can have strong, selective impacts on cortical inhibitory processes, and degrades the ability of the cortex to develop normally-selective characteristics of response (see Strata, Merzenich et al, PNAS, 2005). At the same time, we had dismissed perinatal anoxia as a likely factor contributing to autism’s apparent rise because we could not see how ITS incidence could be growing over the past several decades.
However, it has recently been argued that the especially high susceptibility of the highly metabolically active auditory brainstem to brief periods of anoxia that we and others have documented comes into play in the few to many tens of seconds of oxygen starvation that can stem from very rapid umbilical cord clamping— practices for which have changed (more rapid clamping has been adopted) over the past several decades.”
Dr. Fabrizio Strata, a former postdoctoral fellow from my laboratory who is now an assistant professor at the University of Parma, responded to this post by sending me additional information about the worldwide timing of changes in obstetric practices, noting that earlier clamping of the umbilical cord became the standard of care world-wide beginning in the mid 1980′s, i.e., corresponding to the epoch in which scientists and educators began to first recognize an increase in autism incidence.
Why change an age-old practice invited by Mother Nature or the Creator of the Universe, when it is so obviously a product of 80 million years of natural selection?! Why race to get that clamp on the umbilical cord well before blood flow in the cord stopped on its own? Questioning the wisdom of Mother Nature on a matter like this one, when she’s had billions and billions of births to sort out “what works” for “what doesn’t work” is just a little bit high-handed, one would think. Interestingly, the obstetrics profession itself seems to be questioning the adoption of use of early-clamping procedures, as several important meta-analyses have now shown that late cord clamping (after the umbilical flow has stopped on its own = Nature’s Way) is (big surprise) beneficial to the newborn, with significant positive benefits for late (more natural) cord clamping recorded (in ferritin, which translates to hemoglobin which translates to oxygenation) up to 6 months later (e.g., see Hutton & Hassan, JAMA 297:1241).
It shall be interesting to see whether or not changes in these practices back to the “old way” results in a reduction in autism incidence. Stay tuned — because it looks like the experiment is now underway!
I am a layperson who loves reading this website to learn more about the subject.
Regarding the ultimate cause of autism, your theory about too little oxygen given to children because of changes in standard of care for births in the US, specifically as to how fast the umbilical cord is clamped and cut after birth, can be tested with existing data.
As far as I understand, there have been a large number of births at birth centers (as opposed to full hospitals), where mothers choose to birth in water (usually in some kind of large tub). In these cases, I would assume that the umbilical cord is not clamped quickly. If we look at the autism rates of children born under these circumstances, we could probably perform statistical analysis that would confirm or reject your hypothesis.
The other problem with the perinatal anoxia thesis is that it does not explain the identical / fraternal twin statistical anomaly, as it pertains to autism. Why is it that the concordance of identical twins both having some spectrum disorder is about 90% vs. only 10% in fraternal (Bailey, et. al.) ?
It would be really hard to believe that the clamping of identical twin umbilical cords were all that different from how fraternal twins umbilical cords were clamped?
Fraternal twins typically have different placentas, whereas identical twins share a placenta but have different cords. The blood supply, and pre-clamping susceptibility to anoxia, would surely be different.
There are plenty of reviews associating prenatal or perinatal anoxia with autism already (as well as advanced maternal and/or paternal age). Given that early cord clamping clearly impacts perinatal anoxia, and has been recommended against, it would seem prudent to just change practice and see where that leads in a few years. The evidence that would lead one to think that early cord clamping is a bad idea is elaborate and complex (and amazingly compelling with respect to autism), but changing practice, immediately, is not.
As for the idea that one could statistically detect whether cord clamping is the problem, we can! Amish people do not clamp the cord until placental delivery, and they have no autism rate. The same is true in Somalia, but Somalian immigrants to westernized medical countries have high rates. Try to systematically find out autism rates and immediate cord clamping rates, on a country by country, or region by region basis. It is a task someone should get on immediately, but it will take a lot of effort.