Children born to women with polycystic ovary syndrome (PCOS) may be more likely to develop autism, according to a study.

PCOS is a condition caused by high testosterone which results in delayed onset of puberty, irregular menstrual cycles, and excess bodily hair. Previous studies had shown that autistic children have elevated levels of "sex steroid" hormones including testosterone which "masculinise" the baby's body and brain. Debating on the increase level of hormones, the team found that one possible source may be the mother.

If the mother had higher levels of testosterone than usual, as is the case in women with PCOS, then some of the hormone might cross the placenta during pregnancy, exposing her unborn baby to more of this hormone, and changing the baby's brain development, the findings showed.

"This is an important piece of new evidence for the theory that autism is not only caused by genes but also by prenatal sex steroid hormones such as testosterone," said Adriana Cherskov from the University of Cambridge in Britain. "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," added Simon Baron-Cohen from the varsity.

However, 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, the researchers noted. For the study, published in the journal Translational Psychiatry, the team analysed data from 8,588 women with PCOS and their first-born children, compared to a group of 41,127 women without PCOS. The results showed that women with PCOS had a 2.3 per cent increased chance of having an autistic child.