New research linking high levels of estrogen hormones in the womb and the likelihood of autism development was published yesterday in Molecular Psychiatry. The study, conducted by scientists from the University of Cambridge and the State Serum Institute in Denmark, builds on 20-year old research which first proposed the prenatal sex steroid theory of autism.
In 2015 the Cambridge team measured the levels of four prenatal steroid hormones in amniotic fluids from the Danish Historic Birth Cohort (DHBC), including two androgens. Their results showed a higher quantity of androgen production in male fetuses, which may be one explanation of why autism occurs more frequently in boys.
Their most recent research investigated whether levels of prenatal estrogen hormones—estriol, estradiol, estrone, or estrone sulfate—are associated with autism. The same amniotic fluid samples from the DHBC were used as the 2015 study, which included 98 fetuses who later developed an autism spectrum disorder and 177 who did not.
Their analysis determined that estradiol levels had the highest link to the likelihood of autism development, followed by estriol and estrone. Estrone sulfate did not show any statistical significance. They concluded that high levels of prenatal estrogens were even more predictive of autism development than androgen levels, including testosterone. They predict that elevated fetal steroidogenic activity likely affects sexual differentiation, brain development, and brain function.
In a press release from the University of Cambridge, the authors state that this is the first reported evidence of prenatal estrogens association with autism. Professor Simon Baron-Cohen—who is also the director of the university's Autism Research Center—said, "this new finding supports the idea that increased prenatal sex steroid hormones are one of the potential causes for the condition." He cautions that these findings should not be used to screen for autism. As he told University of Cambridge reporters, their team is "interested in understanding autism, not preventing it."
Regarding the origin of the elevated hormone levels, researcher Alex Tsompanidis told University of Cambridge reporters that, "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."