Presented at the 14th Meeting of the International Society of Prenatal Diagnosis, Vancouver, June 1–4, 2008.
Early first-trimester free β-hCG and PAPP-A serum distributions in monochorionic and dichorionic twins†
Article first published online: 28 JAN 2009
Copyright © 2009 John Wiley & Sons, Ltd.
Special Issue: ISPD Meeting Issue Selected papers from the 14th International Conference on Prenatal Diagnosis and Therapy June 1-4, 2008, Vancouver, Canada
Volume 29, Issue 1, pages 74–78, January 2009
How to Cite
Linskens, I. H., Spreeuwenberg, M. D., Blankenstein, M. A. and van Vugt, J. M. G. (2009), Early first-trimester free β-hCG and PAPP-A serum distributions in monochorionic and dichorionic twins. Prenat. Diagn., 29: 74–78. doi: 10.1002/pd.2184
- Issue published online: 28 JAN 2009
- Article first published online: 28 JAN 2009
- Manuscript Accepted: 11 NOV 2008
- Manuscript Revised: 6 SEP 2008
- Manuscript Received: 3 JUL 2008
- trisomy 21;
- free β-hCG
In the Netherlands, prenatal screening for trisomy 21 in the first trimester of pregnancy for singletons is conducted through a combined test based on maternal age, nuchal translucency measurement and maternal serum free β-hCG and PAPP-A. In our clinic risk calculations in twins are currently based on the NT of both fetuses instead of the combined test. In this study we looked at differences in early first-trimester free β-hCG and PAPP-A between mono- and dichorionic twins.
A total of 202 twin pregnant women participated in the study and agreed to donate first-trimester serum for research.
The data of 200 twins with normal outcome were used for setting up reference values for free β-hCG and PAPP-A. Trisomy 21 was identified in the two remaining pregnancies. The overall median weight-corrected MoM was 1.99 for free β-hCG, and 2.14 for PAPP-A in all twins. Monochorionic twins have a significantly lower free β-hCG weight-corrected MoM (1.53 vs 2.11; Mann-Whitney U, p = 0.002) and a significantly lower PAPP-A weight-corrected MoM (1.59 vs 2.40; Mann-Whitney U, p = 0.003) compared to dichorionic.
This study strengthened the need to make a distinction between mono- and dichorionic twins for the risk calculation in Down syndrome screening as biochemical markers are significantly lower in monochorionic than in dichorionic twins. Copyright © 2009 John Wiley & Sons, Ltd.