Circulating levels of inhibin A, activin A and follistatin in missed and recurrent miscarriages

Background: The aim of this study was to investigate the changes in circulating levels and the clinical use of inhibin A, activin A and follistatin as endocrine markers of early pregnancy loss. Methods: Blood samples were collected from women presenting with a sporadic missed miscarriage (n=10), and controls having pregnancy termination at 8-12 weeks (n=15) and from women with a history of unexplained recurrent miscarriages (n=12) at 6-12 weeks gestation. All samples were assayed for inhibin A, inhibin B, activin A, follistatin, hCG, estradiol and progesterone. Results: Serum inhibin A, hCG, estradiol and progesterone levels were significantly (similar to2-3 fold) decreased in sporadic miscarriages compared with controls. In the recurrent miscarriage group, time dependent changes in plasma inhibin A and hCG levels were significantly (P<0.05) altered in the group that had a subsequent miscarriage compared with those who had a live birth. At 6-7 weeks gestation, plasma inhibin A (similar to 4 fold, P<0.01), hCG (similar to4 fold, P<0.01) and estradiol (similar to 2 fold, P<0.001) levels were significantly lower in women who went on to have another miscarriage than those with a live birth. Inhibin B levels were near the detection limit of the assay. Conclusions: Our findings suggest that inhibin A is a specific marker of early pregnancy loss before the onset of the clinical symptoms of recurrent miscarriage. There is a high degree of association between levels of inhibin A and hCG in cases of miscarriage, indicating that these two proteins could be used in combination to predict future pregnancy outcome.