In utero sex hormone quantities could help predict if a child has autism or not, a new study finds.

“Fetal Estrogens and Autism,” published Monday in the journal Molecular Psychiatry, has discovered a link between estrogen levels and a child’s likelihood to develop autism.

Scientists at the University of Cambridge and Denmark’s State Serum Institute analyzed amniotic fluid samples from 98 mom’s whose fetuses later developed autism. The samples — sourced from the Danish Biobank — had previously been studied by the same group of scientists, when they measured the levels of four prenatal steroid hormones in 2015.

In the 2015 study, the scientists found the hormones were higher in male fetuses who later developed autism. This, in addition to the fact that male fetuses are known to produce more androgens (male-trait inducing hormones) helps explain why autism is more common in males, researchers say.

In the recent study, scientists found that high levels of prenatal estrogens — which includes testosterone — were an even better indicator of autism.

“This new finding supports the idea that increased prenatal sex steroid hormones are one of the potential causes for the condition,” says lead study author Simon Baron-Cohen, director of Cambridge’s Autism Research Centre. “Genetics is well established as another, and these hormones likely interact with genetic factors to affect the developing fetal brain.”

The source of the increased hormone levels is not yet clear — but scientists hope to determine its origin with future research studies.

“These elevated hormones could be coming from the mother, the baby or the placenta, says Cambridge PhD student and study co-author Alex Tsompanidis. “Our next step should be to study all these possible sources and how they interact during pregnancy.”

Scientists say future research should also look at how the study’s findings apply to female fetuses.

“This finding is exciting because the role of estrogens in autism has hardly been studied, and we hope that we can learn more about how they contribute to fetal brain development in further experiments,” says Cambridge researcher Dr. Alexa Pohl. “We still need to see whether the same result holds true in autistic females.”

The findings cannot yet be used to screen for autism, researchers stress: Their answers are only intended and applicable to better understanding the disorder.

“We are interested in understanding autism, not preventing it,” says Baron-Cohen.