Maternal serum activin A, inhibin A, and follistatin in pregnancies with appropriately grown and small-forgestational-age fetuses classified by umbilical artery Doppler ultrasound

Objective: The purpose of this study was to examine the relationship of maternal serum activin A, inhibin A, and follistatin with fetal growth and placental function. Study Design: Inhibin A, activin A, and follistatin were measured in maternal serum that was stored from normally grown (control subjects, N = 50) and small-for-gestational-age pregnancies (n = 49), prospectively classified as normal small-for-gestational-age pregnancy or fetal growth-restricted pregnancy with the use of umbilical artery Doppler ultrasound. Results: Activin A and inhibin A were significantly increased in fetal growth-restricted pregnancies compared with control subjects (activin A: regression coefficient, 0.54, P < .001; inhibin A: regression coefficient, 0.47, P = .003). The activin:follistatin ratio was significantly higher in fetal growth-restricted pregnancies compared with control subjects (P < .001). There were no significant differences between analyte levels of normal small-for-gestational-age pregnancies and control subjects. Conclusion: Maternal serum activin A, inhibin A, and activin:follistatin ratio are raised in fetal growthrestricted pregnancies but not in normal small-for-gestational age pregnancies. This provides further evidence of the difference between subgroups within small-for-gestational-age pregnancies and emphasizes the need to stratify for this in research. (Am J Obstet Gynecol 2002;186:283-7.)