Prenatal Estrogen Levels Linked to Autism: Study

Scientist from the University of Cambridge and the State Serum Institute in Denmark say they have conducted a study that finds that the higher the level of estrogen in a mother’s womb, the higher the likelihood her child will develop autism. 

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The researchers from both university say they have identified a link between exposure to estrogen sex hormones in the womb and the likelihood of developing autism. Their findings, published last week in the journal Molecular Psychiatry, supports the theory, first developed 20 years ago, that says the prenatal sex steroid exposure theory of autism.

Professor Simon Baron-Cohen, director of the Autism Research Centre at the University of Cambridge who led this study and first proposed the prenatal sex steroid theory of autism, said: “This new finding supports the idea that increased prenatal sex steroid hormones are one of the potential causes for the condition. Genetics is well established as another, and these hormones likely interact with genetic factors to affect the developing fetal brain.”

Since the study began in 2015, the scientist have been measuring the levels of four prenatal steroid hormones, including androgens, in the amniotic fluid in wombs of mothers participating in the study. These hormones were higher in male fetuses who later developed autism. Such androgens are generally produced in higher quantities in male than female foetuses, so might also explain why autism occurs more often in boys. 

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In this case, scientists specifically examined estrogens from the amniotic fluid. They found that in 98 fetuses that had four elevated levels of estrogen, all later developed autism, compared to the 177 fetuses that did not. High levels of prenatal estrogens were even more predictive of likelihood of autism than were high levels of prenatal androgens, such as testosterone, said the scientist. 

Estrogen is generally associated with what the scientists call the ‘feminization’ of the brain, but the study concluded that prenatal estrogens have effects on brain growth and the ‘masculinization’ of the brain in many mammals.

Alex Tsompanidis, a Cambridge Ph.D. student who worked on the study, said: “These elevated hormones could be coming from the mother, the baby or the placenta. Our next step should be to study all these possible sources and how they interact during pregnancy.”

Dr. Alexa Pohl, part of the Cambridge team added, “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. We still need to see whether the same result holds true in autistic females.”

However, the team cautioned that these findings cannot and should not be used to screen for autism. “We are interested in understanding autism, not preventing it,” added Professor Baron-Cohen.