AbstractObjectiveTo determine maternal plasma levels of follistatin‐related gene protein (FLRG) in the first trimester of pregnancy and assess its potential role as a marker for prenatal screening of Down syndrome.MethodsMaternal plasma levels of FLRG were determined in 100 pregnant women with normal fetuses in their first trimester of pregnancy (i.e. 11th to 15th weeks). These results were compared with 20 cases with Down syndrome fetuses, taking into consideration clinical and demographic variables, such as maternal age, maternal weight, gestational age, smoking status and ethnicity.ResultsMaternal plasma median of FLRG in the normal population was 1.41 ng/mL with 95% confidence interval (CI) of 1.37–1.70 and interquartile range (IQR) of 0.88, during the 11th to 15th weeks of pregnancy. Maternal age and weight were the only variables significantly related to FLRG levels (p = 0.030 and 0.020, respectively). Only maternal and gestational ages were related to Down syndrome (p = 0.039 and 0.006, respectively). Maternal plasma levels of FLRG were not significantly different in the presence of Down syndrome fetuses compared to normal population (p = 0.63).ConclusionFLRG can be successfully detected in maternal plasma in the first trimester of pregnancy. However, its levels are not significantly altered in the presence of Down syndrome fetuses. Copyright © 2010 John Wiley & Sons, Ltd.