Human chorionic gonadotropin in maternal serum in relation to fetal gender and utero-placental blood flow

BACKGROUND: To investigate whether fetal gender differences in human chorionic gonadotropin (hCG) in maternal serum and the presence of hCG receptors in the wall of the uterine arteries influence the utero-placental blood flow. METHOD AND MATERIAL: Sixty-six healthy women with singleton uncomplicated pregnancies were examined at 8-10, 16-19 and 31-37 weeks of gestation. The pulsatility index (PI) was measured in the uterine arteries, simultaneously with sampling of peripheral maternal blood for hCG determination. Volume flow in the uterine arteries was determined in the second and third trimesters only. RESULTS: In the first and second trimesters no gender differences in the hCG levels were observed. From the second to the third trimester the hCG levels increased significantly in pregnancies with female fetuses (P < 0.05), while in pregnancies with male fetuses the hCG levels tended to decline. The PI declined significantly from the first to the third trimester in both genders (P < 0.001). In the first and third trimesters no gender differences were seen. In the second trimester the PI values were significantly higher in pregnancies with male fetuses than in those with female fetuses (P < 0.02). The flow volume increased significantly in both genders from the second to the third trimester (P < 0.001). In the third trimester the flow volume was higher in pregnancies with female fetuses than in those with male fetuses (P = 0.05). CONCLUSION: The gender differences in uterine artery PI and flow volume were not correlated to maternal serum hCG levels.