From: Dr. Chun Wong
As you know, it is not known exactly what causes a child to develop an autism spectrum disorders and many doctors and scientists, myself included, believe that autism is a multi-factorial disorder, meaning that it can be caused by a number of different factors or a combination of factors. These factors can include environmental factors, genetics, vaccines, food intolerances and pregnancy and birth complications.
Today, I’m going to examine evidence that points to autism spectrum disorders being caused by complications at birth. In their book ” A Parent’s Guide to Asperger Syndrome and High-functioning Autism”, Sally Ozonoff, Geraldine Dawson and James McPartland talk about the link between complications in pregnancy, labor and birth, and autism spectrum disorders, saying that:
“A number of pregnancy, labor and delivery complications have been noted in the histories of children who later turn out to have autism spectrum disorders, such as maternal bleeding during pregnancy, high blood pressure in the mother leading to toxemia, prematurity, and oxygen deprivation during or shortly after birth.”
However, Ozonoff, Dawson and Mc Partland point out that these complications are also found in the birth histories of children with mental retardation, cerebral palsy, speech and language difficulties, and learning disabilities, so they wonder if actually these birth complications cause differences in the brain, rather than autism specifically, or whether actually it is the autism that causes the birth complications.
You might think that it is very strange to believe that it is the autism that causes the pregnancy and birth complications, rather than the other way round, but Ozonoff et al. point out that in the case of Down Syndrome (a disorder that is determined at conception), mothers of babies with Down Syndrome have a higher than average rate of experiencing pregnancy and delivery complications – interesting!
Studies into Birth Complications
There are, however, a number of studies which suggest a link between pregnancy, labor and delivery complications and autism. Here are four examples:
The Utah Study
The University of Utah School of Medicine research team examined the birth records of children in Utah who had been diagnosed with autism spectrum disorders in a CDC (US Centers for Disease Control and Prevention) and found that:-
- Women who are 35 years or older at the time they give birth are 1.7 times more likely to have a child with ASD (autism spectrum disorder) than mothers who are 20-34 years old.
- Autistic children are 1.8 times more likely to be the first born child.
- Autistic children were more than twice as likely to have been born head first (a breech presentation).
The Swedish Study 2002
This study is said to be the largest published study into autism and perinatal factors, and it looked at records of all Swedish children born between 1974 and 1993, and data of autistic children who were discharged from hospital between 1987 and 1994. The study concluded that the risk of autism was “significantly associated” with:-
- Birth by C-section
- A score of below 7 on the 5-minute Apgar test
- Birth taking place outside Europe or North America
- Bleeding during pregnancy
- Smoking daily in early pregnancy
- The baby being small for its gestational age
- Congenital malformations
Labor induction did not appear on the records used (the Birth Register) until after 1991 and so could not be taken into account in the study.
The Danish Study
“Risk Factors for Autism: Perinatal Factors, Parental Psychiatric History and Socioeconomic Status” carried out in Denmark by H J Larsson et al. was a study that examined the data of 698 children who were born after the year 1972 and who had been discharged from Danish psychiatric hospitals after being diagnosed with “infantile or atypical autism” up until November 1999. The study also looked at the records of the children’s parents. The study was published in the May 2005 edition of the American Journal of Epidemiology and found that the following factors significantly increased the risk of autism:-
- Breech presentation
- An Apgar score of below 7 in the 5-minute test
- A birth weight of below 2,500g
- A baby being born at a gestational age of less than 35 weeks
- A baby being small for its gestational age
- The mother being aged over 30 and the father being over 35
- A family history of schizophrenia
Researchers did mention that other factors could be involved, such as external environmental exposures or specific genotypes and that also an autistic child may “react differently to the intrauterine environment, leading to fetal distress during the last part of pregnancy and during delivery”.
The US Center for Disease Control and Prevention Report
Researchers from the US Center for Disease Control and Prevention compared 565 autistic children with 578 children of the same age, but without autism, who were born between 1981 and 1993 in the Atlanta area. Researchers found that:-
- Autism was less common than cerebral palsy, hearing or vision loss, and other developmental disabilities in low birthweight and preterm children.
- Autism was twice as likely in children born weighing less than 2,500g (about 5.5 pounds) than those with a normal birth weight.
- Autism was twice as likely in children born before 33 weeks of pregnancy than those born at full term.
- Girls were particularly at risk with low birth weight girls being 4 times more likely, than girls born at normal weights, to have autism with some type of mental retardation or other developmental disabilities.
The researchers are continuing to investigate these findings in a 5 year study of about 2,700 children.
The fact that these studies all looked at a large number of children, that they looked at children from different countries and yet came up with similar hypotheses makes them very believable and it does look like complications during pregnancy, labor or birth do have a part to play in a child developing an autism spectrum disorder. However, it is certainly not the only factor contributing to our present autism epidemic. We must take into account other factors such as:-
- Heavy metals and environmental toxins
- Nutritional deficiencies
- Food intolerances
- Yeast overgrowth
- Mitochondrial dysfunction
- Gut problems
We need to keep an open mind and make sure that all factors are researched.