The aromatase enzyme, which is encoded by a gene member of the cytochrome P450 family enzyme, subfamily A, polypeptide 1 ( CYP19A1), is about 130 kb long, and located on chromosome 15q21. Presumably, the presence of the aromatase enzyme in the placenta, converting androgens into estrogens, protects the female fetus from direct transfer of maternal testosterone ( 18). Generally, maternal testosterone levels are not correlated with the testosterone concentration in the fetal circulation, at least not in conjunction with delivery when the fetal circulation becomes accessible for assessment ( 15, 16, 17). However, the relationship between maternal androgen levels and maternal BMI, weight gain and depression are still less well explored ( 14). In addition, young maternal age is associated with higher testosterone levels in pregnancy ( 11, 12, 13). Maternal serum testosterone concentrations increase by 70% during pregnancy ( 7) and are increased to an even greater degree in women with PCOS ( 8, 9) and preeclampsia ( 10). Yet, little is known about how such androgen exposure would occur in humans.
Sheep ( 2), monkeys ( 3), rats ( 4) and mice ( 5, 6) prenatally treated with testosterone or dihydro-testosterone exhibit ovarian and endocrine traits similar to women with PCOS, such as LH hypersecretion, enlarged polyfollicular ovaries and functional hyperandrogenism. However, increased levels of testosterone during fetal life are also suggested as one of the potential causes of PCOS development. Most of the evidence concerning human behavior comes from studies on women with congenital adrenal hyperplasia (CAH), who during childhood and adolescence display increased male-typical toy-, play- and playmate preferences ( 1). Testosterone plays an important role in the organization and sexual differentiation of the brain during early fetal development, and exposure to high levels of testosterone during critical periods of fetal life promotes behavioral masculinization in a variety of mammals ( 1). The impact of prenatal testosterone exposure has been a focus of interest in the last decades.