STEROIDS IN HUMAN INTRAUTERINE FLUIDS OF EARLY-PREGNANCY

OBJECTIVE Little is known of the hormone environment of the developing early human embryo. We have therefore measured selected steroids in t he intrauterine fluids of early pregnancy. DESIGN Measurement of proge sterone, 17 alpha-hydroxyprogesterone, oestradiol-17 beta, testosteron e, androstenedione, cortisol and dehydroepiandrosterone sulphate in ma tched samples of coelomic fluid, amniotic fluid and maternal serum col lected before pregnancy termination from 12 women between 8 and 12 wee ks gestation. RESULTS Mean concentrations of progesterone, oestradiol- 17 beta and 17 alpha-hydroxyprogesterone in coelomic fluid were respec tively 20, 6 and 2 times greater than in maternal serum and 8, 13 and 2.6 times those in amniotic fluid. Concentrations of testosterone and androstenedione were highest in maternal serum and lowest in amniotic fluid. Cortisol and dehydroepiandrosterone sulphate were found in intr auterine fluids only at the limit of detection but in normal concentra tions in maternal serum. CONCLUSIONS Coelomic fluid contains relativel y high concentrations of progesterone, oestradiol-17 beta and 17 alpha -hydroxyprogesterone which may be synthesized locally. Amniotic fluid contains lower concentrations of steroids (other than progesterone) th an are found in coelomic fluid or maternal serum. Free diffusion of st eroids across the amnion appears limited. This may constitute a mechan ism to protect the embryo from unwanted exposure to biologically activ e steroids.