Serum DHAS in the maternal-fetoplacental system during the 28th-40th weeks of pregnancy

The authors measured the serum levels of dehydroepiandrosterone sulfate (DHAS) in the maternal vein (MV), the umbilical vein (UV) and the umbilical artery (UA) during the 28th-36th weeks of pregnancy (n = 74) and in the 40th week (n = 34), to clarify the hormonal changes that occur between the maternal and fetal compartments. The following results were found: (1) The DHAS concentration increased significantly in MV, up to twice the concentration from the 28th-32nd weeks to the 33rd-36th weeks (p less than 0.01). From the 33rd-36th weeks to the 40th week it decreased significantly to one third of this value (p less than 0.01). DHAS levels revealed a decreasing tendency in the UA and UV serum from the 28th-32nd weeks to the 33rd-36th weeks, and there was a tendency to rise from the 33rd-36th weeks to the 40th week. (2) The serum DHAS values were found to be higher than in the MV, the UA-UV difference was not significant; however, the 'UA/UV X 100' value remained higher than 100% during the 28th-40th weeks. (3) The MV DHAS value showed slight correlation with the UV and UA DHAS concentration (r = 0.2951, p less than 0.01, n = 106; r = 0.2930, p less than 0.01, n = 100). There was a close correlation between the UV and UA serum DHAS levels (r = 0.8432, p less than 0.01, n = 98). The authors consider that the adrenal activity increases independently of the maternal adrenal cortex at term.