Other causes of hyperandrogenism during pregnancy include worsening of symptoms in patients with pre-existing PCOS, which usually manifests during the first trimester, benign and malignant tumours of the ovaries, which invariably cause virilisation, maternal exposure to androgenic drugs, congenital adrenal hyperplasia, maternal or foetal adrenal tumours and placental aromatase deficiency. This evidence concerns the gene CYP19A1 and congenital adrenal hyperplasia.