Recent research has suggested that exposure to certain sex hormones early in life is linked with an increased risk of autism spectrum disorder, and data from a new large study published in Molecular Psychiatry is adding to this notion. Children born from mothers with the endocrine system disorder, Polycystic Ovary Syndrome (PCOS) were found to have a 59% higher risk of developing autism. If the mother was also obese, the risk increased further. The researchers believe the reason for this increase could be that PCOS is characterized by a hormone imbalance that includes higher levels of the sex hormone androgen. The roles of androgen include development of the brain and central nervous system, as well as development of male characteristics. If the PCOS-autism link is confirmed, it would provide evidence that the development of autism begins before birth. Hormone imbalance in women with PCOS can create irregular menstrual cycles, ovarian cysts and difficulty becoming pregnant. Between 5% and 15% of women of childbearing age have PCOS. Although the study was not designed to show a causal relationship, the discovery of a compelling link between PCOS and autism may lead to medical professionals keeping a watchful eye on the offspring of women with PCOS in the future.