Maternal serum activin A and the prediction of intrauterine growth restriction

Background: Differentiating between the small healthy fetus and the high risk growth restricted fetus remains a significant obstetric challenge. It has been previously shown that maternal activin A levels are increased in association with fetal growth restriction. Aim: To evaluate maternal serum activin A as a marker of fetal growth restriction. Methods: Prospective cohort study of 62 women referred for fetal assessment because of a clinical suspicion of a small for gestation fetus. Maternal serum levels of activin A were measured with an ELISA. Results: Activin A levels, expressed as median (95% CI) MoMs, were similar in the women with a normal-sized fetus and in those with a healthy small for gestational age fetus, 1.14 (95% CI 1.0-1.5) and 1.31 (95% CI 0.8-2.1), respectively (P = 0.97). Compared to the women with a normal-sized fetus or a healthy small fetus, activin A levels were significantly elevated in the women who had an intrauterine fetal growth restriction fetus 2.37 (95% CI 1.6-3.7; P = 0.01 compared to normal and P = 0.04 compared to healthy small). Conclusions: These data confirm that circulating activin A is increased in association with fetal growth restriction. However, a single blood sample for activin A will not efficiently discern between healthy and compromised small fetuses.