Maliqueo M, et al. – Researchers aimed to correlate sex steroid concentrations and placental expression of steroidogenic enzymes between non–obese and obese pregnant women with non–pathological pregnancies, and investigated the influence of fetal gender on these parameters. The obtained data demonstrate that obesity in non–pathological pregnancies alters the maternal serum progesterone and testosterone concentrations depending on fetal gender. These alterations can be attributed to gender–related placental adaptations, as the expression of P450 aromatase is different in placentas from females compared to males.