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 growth-restricted 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.