a woman holding a baby boyWhat causes autism? Scientists from Cambridge and Copenhagen conducted a study to analyze the relationship between autism spectrum disorders (ASD) and hormones present in the womb during fetal development. They discovered that children with autism were exposed to a much larger amount of hormones like testosterone while in the womb. The findings contribute to mounting evidence suggesting that autism is the result of complex environmental factors that affect development in utero.

The researchers gathered data from Danish medical records and biobank material. They collected amniotic fluid samples for 128 boys diagnosed with ASD and for a number of boys without ASD. Anmniotic fluid surrounds and sustains a fetus in the womb. The amniotic fluid samples were from medical tests for amniocentesis that were conducted while the women were pregnant.

Boys with autism were more likely to be exposed to higher levels of hormones during fetal development, specifically to higher levels of “sex steroids” like progesterone and testosterone. They were also exposed to higher levels of cortisol, the hormone related to stress.

In the womb, boys produce about twice as much testosterone as girls, but compared with typical boys, the autism group has even higher levels. It’s a significant difference and may have a large effect on brain development,” commented Simon Baron-Cohen, director of Cambridge University’s Autism Research Centre.

The researchers do not suggest that hormones in the amniotic fluid are a direct cause of autism, but the findings may explain why boys are significantly more likely than girls to develop ASD. These results also suggest that autism is caused by prenatal conditions. The researchers state that the purpose of the research is not to establish a test for autism, but only to catalog one possible cause of the disorder. This research is published in the journal Molecular Psychiatry.
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