INHIBIN-A AND ACTIVIN-A IN THE FIRST-TRIMESTER OF HUMAN-PREGNANCY

Recent studies show that high concentrations of inhibin A and activin A are present in the maternal serum throughout human pregnancy. The ai m of this study was to determine whether the corpus luteum produces si gnificant quantities of inhibin A and activin A during the first trime ster of pregnancy. This prospective study examined two groups of women who had blood samples taken from 5-12 weeks gestation. One group cons isted of 14 women with donor egg pregnancies (8 singletons and 6 multi ples) who did not have corpora lutea, and the other group consisted 5 women with spontaneous pregnancies who had corpora lutea. Inhibin A an d activin A were measured at weekly intervals using specific enzyme im munoassays. All pregnancies progressed to term, with healthy babies be ing delivered. Maternal serum concentrations of inhibin A significantl y increased throughout the study period in the donor egg pregnancies ( P < 0.001) and the control pregnancies (P < 0.001). Circulating concen trations of activin A also increased significantly in both the spontan eous and donor egg pregnancies (P < 0.001) during the study period. Ho wever, the concentrations of inhibin A and activin A in the first trim ester of human pregnancy were not significantly different in the women with or without corpora lutea, suggesting a fetoplacental origin. mul tiple donor egg pregnancies were found to have higher concentrations o f inhibin A (P < 0.001) and activin A (P < 0.05) compared with singlet on donor egg pregnancies, which also supports a placental source.