Nuchal translucency measurements are highly correlated in both mono- and dichorionic twin pairs
Article first published online: 31 JAN 2006
Copyright © 2006 John Wiley & Sons, Ltd.
Volume 26, Issue 3, pages 218–220, March 2006
How to Cite
Wøjdemann, K. R., Larsen, S. O., Shalmi, A.-C., Sundberg, K., Tabor, A. and Christiansen, M. (2006), Nuchal translucency measurements are highly correlated in both mono- and dichorionic twin pairs. Prenat. Diagn., 26: 218–220. doi: 10.1002/pd.1382
- Issue published online: 28 FEB 2006
- Article first published online: 31 JAN 2006
- Manuscript Accepted: 15 NOV 2005
- Manuscript Received: 9 NOV 2005
- Manuscript Revised: 9 NOV 2005
- Down syndrome;
- first trimester;
- nuchal translucency;
- serum markers;
To establish the distribution of serological and ultrasound first-trimester Down syndrome markers in twins and identify correlations of significance for risk calculation.
Nuchal translucency (NT), PAPP-A and βhCG data were extracted from 181 twin pregnancies (31 mono- and 150 dichorionic) with a normal outcome. All pregnancies were consecutively and prospectively included and examined in the Copenhagen First-Trimester Study. The variance of the sum and the difference of log MoM NT values in twin pairs was used to calculate the correlation.
The serological markers did not correlate and were nearly twice the value seen in singleton pregnancies with a median PAPP-A MoM of 2.14 and a median free βhCG MoM of 2.06. Chorionicity was not found to influence the level of biochemical markers. In all twin pairs (r = 0.343, p < 0.001, F-test), as well as mono- (r = 0.404, p = 0.011, F-test) and dichorionic twins (r = 0.316, p < 0.001, F-test) there was a significant correlation between log MoM NT in each pair.
As the NT values of fetuses in subsequent pregnancies from the same woman do not correlate, the correlation between NTs in twins reflects that the NT is influenced by placental and maternal factors specific for the particular pregnancy, for example, nutrient supply or vascularisation. The correlation may be useful to improve the precision of the prenatal risk assessment for Down syndrome in first-trimester twin pregnancies. The serological markers were elevated in the examined twins as previously described. Copyright © 2006 John Wiley & Sons, Ltd.