Simultaneous determination of seven unconjugated steroids in maternal venous and umbilical arterial and venous serum in elective and emergency cesarean section at term.

In order to assess specific gluco- and mineralocorticoid functions in both mother and fetoplacental unit in relation to the presence or absence of labor, serum levels of unconjugated aldosterone (A), corticosterone (B), deoxycorticosterone (DOC), progesterone (P), 17-hydroxyprogesterone (17-OHP), cortisol (F), and cortisone (E) were determined simultaneously. These levels were determined by specific radioimmunoassays in two groups of 24 paired maternal venous and umbilical arterial and venous samples obtained at term delivery by either elective (Group I, N = 8) or emergency (Group II, N = 8) cesarean section. In Group II, after spontaneous labor, mean maternal serum levels of all steroids investigated exceeded those found in Group I (not in labor). These increases were most pronounced (p less than 0.005) in F (74%) and DOC (106%) levels demonstrating stimulation of both the glucocorticoid (cortisol)--and the mineralocorticoid (aldosterone)--producing pathways of the maternal adrenals by spontaneous labor. Arteriovenous differences in umbilical steroid levels revealed in both groups the placental origin of P, 17-OHP, and E (p less than 0.05 to 0.005), with greater (more negative) mean AV differences after labor (Group II). The negative AV difference of DOC, B, A, and F found in Group I, however, decreased after labor and became even positive in the cases of B and F, reflecting the close relationship between spontaneous labor and the fetal adrenal's active production not only of the glucocorticoids B and F, but also, to a lesser extent, of the mineralocorticoids DOC and aldosterone.