Objective To assess maternal serum activin A as a potential marker of fetal growth restriction.
Design A cohort study.
Setting A maternal–fetal medicine unit, university teaching hospital.
Population Fifty-seven women with a small fetus (less than 10th centile for gestation) referred for assessment of fetal size by ultrasound biometry.
Methods At the time of presentation for fetal biometry, maternal blood was collected for activin A measurement. The case records of each woman were independently reviewed after delivery and the pregnancy grouped into one of three groups: constitutionally small fetus, intrauterine growth restricted (IUGR) fetus or IUGR fetus and maternal pre-eclampsia (IUGR–pre-eclampsia). Activin A levels in the three groups were compared.
Main outcome measures Maternal serum activin A levels.
Results Sixteen of the 57 pregnancies were classified as constitutionally small, 17 as IUGR and 24 as IUGR–pre-eclampsia. Expressed as multiples of a normal median (MoMs), the median (95% CI) activin A level in the constitutionally small pregnancies was 1.12 (0.72–1.39) MoMs significantly lower than the level in both the IUGR pregnancies, 3.00 (1.84–4.11) MoMs, and the IUGR–pre-eclampsia pregnancies, 7.96 (5.73–10.62) MoMs (P= 0.002 and 0.0001 for IUGR vs constitutionally small and IUGR–pre-eclampsia vs constitutionally small, respectively).
Conclusions Maternal serum activin A may be useful in the assessment of the small for gestational age fetus.