The study team developed on their previous findings by collecting the same 98 individual amniotic fluid samples from the Danish Biobank, which they previously used. The Danish biobank has collected amniotic samples from more than 100,000 pregnancies. However, the study focused on estrogen, the prenatal sex steroid hormone.

The study team used Pearson’s correlation coefficient to calculate the matrix correlation of all assayed steroid hormones. They examined the univariate distribution of the estrogens, and all the hormones displayed a rightward skew. The Box-Cox procedure was used to transform the oestrogens to reduce their skew because their statistical power of logistic regression is affected by the predictor variable. Also, the univariate logistic regression model was utilized to determine if each hormone increased autism possibility in this cohort.