Background: The objective of the study was to examine the relationship between the concentrations of maternal serum AFP, total β-hCG and uE3 and the presence of various pathologies of the feto-placental unit.
Material/Methods: The triple test was performed in the group of 882 pregnant women between the 14th and 21st week of gestation. The control group consisted of 863 pregnant women with unburdened obstetric anamnesis with an uneventful singleton pregnancy. The examined group consisted of 19 pregnant women with fetal aneuploidies and other pathologies of the feto-placental unit (oligohydramnios, vacuolization of the trophoblast). In the maternal sera concentrations of AFP, total β-hCG and unconjugated estriol were determined. The risk of fetal trisomy 21 was calculated using DOWNS and PRISCA 3.0 software (cut-off 1: 295), Ulm Index was also calculated (cut-off 8.1).
Results: In the group of pregnant women with fetal chromosomal aneuploidies no significant changes of the examined parameters were established. In the cases of oligohydramnios AFP concentrations significantly increased, in the cases of fetal triploidy the concentrations of all examined parameters decreased. In the cases of vacuolization of the trophoblast concentration of the total β-hCG increased.
Conclusions: Oligohydramnios, fetal triploidy and vacuolization of the trophoblast caused significant changes of the concentrations AFP, total β-hCG and unconjugated estriol in maternal sera.

Keywords: feto-placental unit, fetal chromosomal aneuploidies, maternal serum, unconjugated estriol, total beta-hCG, alfa-fetoprotein