Women with polycystic ovary syndrome (PCOS) are more likely than other women to have an autistic child, according to an analysis of NHS data carried out by Cambridge University.
The researchers, from the university’s Autism Research Centre, noted that PCOS affected about one in 10 women and was caused by elevated levels of the hormone testosterone.
“This new research is helping us understand the effects of testosterone on the developing foetal brain”
The had previously published work in 2015 showing that before they were born, autistic children had elevated levels of “sex steroid” hormones, which “masculinised” the baby’s body and brain.
The discovery that prenatal sex steroid hormones were involved in the development of autism was one possible explanation for why autism is diagnosed more often in boys.
The researchers then wondered where these elevated sex steroid hormones were coming from, with one possible source being the mother.
For example, if she had higher levels of testosterone than usual, as with PCOS, then some of the hormone might cross the placenta, exposing the baby to more of it and changing brain development.
Using anonymous data from a large database of GP records, the study looked at 8,588 women with PCOS and their first-born children, compared to a group of 41,127 women without PCOS.
“We need to think about the practical steps we can put in place to support women with PCOS”
The team found that, even after taking into account other factors, women with PCOS had a 2.3% chance of having an autistic child, compared with the 1.7% chance for mothers without PCOS.
They stressed that the likelihood of having an autistic child was still very low, even among those with PCOS – but finding the link provided an “important clue” on the multiple causal factors of autism.
Their study, published today in the journal Translational Psychiatry, was supported, among others, by the Autism Research Trust, the Medical Research Council and the Wellcome Trust.
They previously presented their findings at the International Meeting for Autism Research in 2016, and their findings were replicated in a Swedish study in the same year.
The team also conducted two other studies using the same data and found that autistic women were more likely to have PCOS, and women with PCOS were more likely to have autism themselves.
This strongly suggests that these two conditions are linked, probably because they both share elevated sex steroid hormone levels, they said.
“This is an important step in trying to understand what causes autism”
Senior study author Professor Simon Baron-Cohen, director of the Autism Research Centre, said: “This new research is helping us understand the effects of testosterone on the developing foetal brain, and on the child’s later behaviour and mind.
“These hormonal effects are not necessarily independent of genetic factors, as a mother or her baby may have higher levels of the hormone for genetic reasons, and testosterone can affect how genes function,” he said.
Study co-author Dr Carrie Allison said: “We need to think about the practical steps we can put in place to support women with PCOS as they go through their pregnancies.
“The likelihood is statistically significant but nevertheless still small, in that most women with PCOS won’t have a child with autism, but we want to be transparent with this new information,” she said.
Another co-author, Dr Rupert Payne, from the University of Bristol Centre for Academic Primary Care, added: “This is an important step in trying to understand what causes autism.”