Obesity during pregnancy affects sex steroid concentrations depending on fetal gender

BACKGROUND/OBJECTIVE: It is not clear whether maternal obesity along with fetal gender affect sex steroid metabolism during pregnancy. Therefore, we compared 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. METHODS: In 35 normal weight (body mass index (BMI) 20-24.9 kg m(-2)) (controls) and 36 obese women (BMI 30-36 kg m(-2)) (obese), a fasting blood sample was obtained at first and at third trimester of gestation to measure progesterone, dehydroepiandrosterone (DHEA), DHEA sulfate, androstenedione, testosterone and estradiol by liquid chromatography-tandem mass spectrometry and estrone by radioimmunoassay. In a subset of women, placental mRNA and protein expression of steroidogenic enzymes was measured by quantitative PCR and western blot, respectively. The comparisons were primarily made between controls and obese, and then separately according to fetal gender. RESULTS: At first and third trimesters of gestation serum progesterone was lower whereas testosterone was higher in obese women (P < 0.05, respectively). Upon analyzing according to fetal gender, lower progesterone levels were present in obese pregnant women with male fetuses at first trimester and with female fetuses at third trimester (P < 0.05, respectively). Testosterone was higher in obese women with male fetuses compared to control women with male fetuses (P < 0.05). The placental protein expression of P450scc was higher in obese women compared to controls (P < 0.05). P450 aromatase was higher in obese women with female fetuses (P = 0.009), whereas in obese women with male fetuses P450 aromatase was lower compared to control women (P = 0.026). CONCLUSIONS: Obesity in non-pathological pregnancies alters the maternal serum progesterone and testosterone concentrations depending on fetal gender. These changes can be attributed to gender-related placental adaptations, as the expression of P450 aromatase is different in placentas from females compared to males.