A new study has found that high testosterone exposure in the womb increases the risk of autism in children.
Researchers at Fiona Stanley's Telethon Institute for Child Health Research found that girls with autistic-like behaviours at age two had their first period about six months later than girls without the disorder's symptoms.
The study looked at 383 girls who had no diagnosis of autism. At age two they were each given a rating for showing autistic-like behaviours such as avoiding looking people in the eye.
"These findings indicate that exposure to testosterone in the womb may be regulating both autism-like behaviours and the age of first period and that this may play a role in clinical autism," The Australian quoted lead researcher Andrew Whitehouse as saying.
Whitehouse added that the results were linked to the so-called "male brain theory" of autism, which suggests the behaviour disorder is an extreme form of male mental traits.
"Autism is a real male-dominated condition; it affects around four males to one female, but there are also characteristics of people with autism that are more male-like," he said.
"People have started thinking what might cause that, and the obvious candidate is male-type hormones and the most biologically active is testosterone."
Whitehouse's team now plans to conduct a world-first study to further examine the link.