Maternal age-specific risks for trisomies at 9—14 weeks' gestation
Article first published online: 22 NOV 2005
Copyright © 1994 John Wiley & Sons, Ltd.
Volume 14, Issue 7, pages 543–552, July 1994
How to Cite
Snijders, R. J. M., Holzgreve, W., Cuckle, H. and Nicolaides, K. H. (1994), Maternal age-specific risks for trisomies at 9—14 weeks' gestation. Prenat. Diagn., 14: 543–552. doi: 10.1002/pd.1970140706
- Issue published online: 22 NOV 2005
- Article first published online: 22 NOV 2005
- Manuscript Accepted: 31 DEC 1993
- Manuscript Revised: 18 OCT 1993
- Manuscript Received: 22 JUL 1993
- First trimester of pregnancy;
- fetal trisomies;
- maternal age
This study provides data on the incidence of fetal trisomies 21, 18, and 13 at 9–14 weeks' gestation in women aged 35–45 years and estimates of maternal age-specific risks in women aged 20–45 years. Our data from 5814 singleton pregnancies undergoing first-trimester karyotyping for the sole indication of maternal age ⩾ 35 years were combined with those from two previous reports and the incidence of the trisomies was calculated from a total of 15 793 pregnancies. Comparison of incidences at 9–14 weeks' gestation with published data at 15–20 weeks' gestation and in livebirths demonstrated that at birth the maternal age-specific incidence of trisomy 21 is 33 per cent lower than at 15–20 weeks' gestation and 54 per cent lower than at 9–14 weeks' gestation. Furthermore, the relative frequency of trisomies 18 and 13 decreases from 30 per cent at 9–14 weeks to 22 per cent at 15–20 weeks and 14 per cent at birth.