Maternal serum levels of total activin-A in first-trimester trisomy 21 pregnancies

Maternal serum total activin-A concentration was measured in 45 pregnancies affected by trisomy 21 and il 93 control unaffected pregnancies at 10-14 w eeks of gestation. In the trisomy 21 pregnancies total activin-A concentrat ion was significantly higher (1.36 MoM of the unaffected pregnancies) and i n 16% of cases the level was above the 95th centile of normal. The log(10) SD for the control group and the trisomy 21 group were 0.17 and 0.22. respe ctively. The median pregnancy associated plasma protein-A (PAPP-A) in this trisomy 21 series was 0.49 and for free beta -hCG was 2.05. In the trisomy group there were significant positive associations between total activin-A and PAPP-A (0.6071) and free beta -hCG (0.4255). The low median difference and the high overlap in values between trisomic and unaffected pregnancies make total activin-A of little practical use in first-trimester screening f or trisomy 21. Copyright (C) 2001 John Wiley & Sons, Ltd.