This post is the third in a series about results from the EARLI study - a unique, long-term prospective study of prenatal autism spectrum disorder risk factors and markers. Launched in 2008, the EARLI study is one of the most extensive ongoing epidemiologic studies to understand the complex causes of autism.

Males are about four times as likely as females to be diagnosed with autism, but experts still don’t know why. To explore one aspect of this phenomenon, researchers looked at prenatal exposure levels to male sex hormones called androgens, which they thought might shed light on the causes of autism. They looked at umbilical cord blood samples from 137 children in the EARLI study to measure several male sex hormones. Then, they correlated these hormone levels with scores on two tools, one to screen for autism in infants whose older siblings have autism and a second that identifies social impairment within the autism spectrum.

Researchers didn’t find an association between androgen level and scores on the two tools. They did find, however, that infants with an older female sibling with autism had higher levels of testosterone and more severe autism traits. This implies that the role androgen might play in the cause of autism depends largely on genetics, but much more research needs to be done to explore this relationship.