Study claims autism linked to high oestrogen levels in the womb

29 Jul 2019

Image: © Syda Productions/

Having high levels of oestrogen in the womb could increase the chances of a child developing autism, researchers claim.

A team of scientists from the University of Cambridge has published a paper to Molecular Psychiatry that claims to have found a new link that could indicate during pregnancy whether a foetus will develop autism, but warns that these findings should not be used to screen for it.

In the study, the team said that it had identified a link between exposure to high levels of oestrogen sex hormones in the womb and the development of autism.

In 2015, the same team – working with the State Serum Institute in Denmark – measured the levels of prenatal steroid hormones, including two known as androgens, in the amniotic fluid in the womb.

These were discovered to be higher in boys who later developed autism. Because they are produced in higher quantities in males on average, it was thought this might explain why autism often occurs more in boys.

For this latest study, the team used the same amniotic fluid samples from the Danish National Biobank, which has collected samples from more than 100,000 pregnancies. This time, it looked at the prenatal sex steroid hormones called oestrogens.

Role of oestrogen has hardly been studied

The results showed that all four oestrogens were, on average, significantly elevated in the 98 foetuses that later developed autism, compared to the 177 foetuses that did not.

High levels of prenatal oestrogen were found to be even more predictive of autism than prenatal androgens, such as testosterone. Contrary to popular belief that associates oestrogens with feminisation, prenatal oestrogens have effects on brain growth and also masculinise the brain in many mammals.

Prof Simon Baron-Cohen, director of the Autism Research Centre at the University of Cambridge and leader of this study, 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 foetal brain.”

Another researcher on the team, Dr Alexa Pohl, said this discovery was “exciting” because the role of oestrogens in autism has hardly been studied.

Looking to the future, the team wants to determine the source of these elevated hormones, whether it be the mother, baby or placenta.

However, Baron-Cohen warned that this discovery should not lead to the development of screening for autism. “We are interested in understanding autism, not preventing it,” he said.

Colm Gorey was a senior journalist with Silicon Republic