According to a study published in the journal Molecular Psychiatry, scientists have identified a new factor linked to autism, adding further evidence to support a theory first proposed two decades ago. In 2015, scientists from the University of Cambridge and the State Serum Institute in Denmark studied prenatal steroid hormones. They measured the levels of four different hormones, including two known as androgens, in the amniotic fluid in the womb. The study showed they were higher in male fetuses who developed autism later on in life. The androgens are also produced in higher quantities in male fetuses, compared to female fetuses. Scientists proposed this as a possible explanation to why autism occurs more in males.
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In the most recent study, scientists built on these findings by testing the amniotic fluid samples from the same individuals sampled from the Danish Biobank. This time, they studied another set of prenatal sex steroid hormones — estrogens. The four estrogens tested were all found to be significantly elevated, on average, in the 98 fetuses who later developed autism, compared to the 177 who did not. The study also showed that high levels of prenatal estrogens were even more predictive, compared to high levels of prenatal androgens, of the likelihood of autism.
Study leader professor Simon Baron-Cohen, director of the Autism Research Center at the University of Cambridge, first proposed the prenatal sex steroid theory of autism. He said, “This new finding supports the idea that increased prenatal sex steroid hormones are one of the potential causes for the condition. Genetics is well established as another, and these hormones likely interact with genetic factors to affect the developing fetal brain.”
Researchers say the next step is to determine the source of the elevated hormone levels, which could be coming from the mother, the baby or the placenta.
According to the CDC, approximately 1 in 59 children is diagnosed with an autism spectrum disorder. That number includes 1 in 151 girls and 1 in 37 boys. In 1985, children routinely received 23 doses of seven vaccines: diphtheria-tetanus-pertussis (DTP), oral polio (OPV) and measles-mumps-rubella (MMR), and the autism rate was between 1 in 5,000 or 1 in 10,000 (depending on the data source). Today, the CDC recommends that infants and children receive 49 doses of 14 vaccines by age 6.