Sialic acid, steroid and proteohormones in maternal, cord and retroplacental blood

Background: To study the storage of sialic acid in newborns reference conce ntrations for sialic acid were measured in maternal, retroplacental and cor d blood and compared with the concentration of human placental lactogen (hP L) and estriol (E3). High serum concentrations of hPL and E3 in retroplacen tal blood indicate the synthesis of these products in the fetoplacental uni t. The comparison of the serum concentrations give first informations for a possible role of the placenta as a place of production and storage of the investigated products. Methods: The concentrations of sialic acid, hPL and unconjugated E3 were de termined in maternal and retroplacental blood samples of 126 pregnant women (16-42 years old) between 28 and 42 weeks of gestation. 84 of these pregna nt women had uncomplicated pregnancy with birth after 37 gestational weeks. Measurements of E3 and hPL were performed by solid phase radioimmunoassays . Concentrations of sialic acid were determined by HPLC thigh performance l iquid chromatography). Results: Means and medians of the three parameters for both groups differen tiate hardly. The retroplacental serum concentrations of hPL and E3 are inc reased significantly compared with maternal blood. The same trend was found for sialic acid without significance. The highest concentrations of E3 wer e found in the cord blood (298.2+/-138.0 ng/ml) (p < 0.01). On the other ha nd the lowest concentrations of sialic acid (36.1+/-19.6mg/l) (p < 0.01) we re estimated in cord blood samples. It was estimated a significant correlat ion between fetal and retroplacental concentrations of E3. Significant corr elations (p < 0.01) were found for sialic acid between maternal and retropl acental blood on the one side and maternal and the cord blood on the other side. Significant increased mean sialic acid concentrations in retroplacent al blood (x = 102.67 mg/l) were found in female newborns in comparison with male newborns (x = 80.58 mg/l). There were not significant differences bet ween prematurity and term delivery. Conclusion: Increased sialic acid concentrations in retroplacental blood sa mples are a sign of sialic acid accumulation in the fetomaternal area aimin g to induce the tolerance of fetal allotransplantat. There are no evidence for a take up of free sialic acid by fetus.