Scientist have identified a link between exposure to high levels of oestrogen sex hormones in the womb and the likelihood of developing autism. The findings are published today in the journal Molecular Psychiatry.
The discovery adds further evidence to support the prenatal sex steroid theory of autism first proposed 20 years ago.
In 2015, a team of scientists at the University of Cambridge and the State Serum Institute in Denmark measured the levels of four prenatal steroid hormones, including two known as androgens, in the amniotic fluid in the womb and discovered that they were higher in male foetuses who later developed autism. These androgens are produced in higher quantities in male than in female foetuses on average, so might also explain why autism occurs more often in boys. They are also known to masculinise parts of the brain, and to have effects on the number of connections between brain cells.