Outcome12 week group18 week groupP value
Prevalence rate55/19 796 (0.28%)43/19 776 (0.22%)0.18
Rate of liveborn babies with DS (at ≥ 22 weeks)10/19 796 (0.05%)16/19 776 (0.08%)0.25
Antenatal detection rate (< 22 weeks in living fetus)42/55 (76%)25/41a (61%)0.12
Antenatal detection rate (if karyotyping performed only for defined policy)39/55 (71%)21/41a (51%)0.06
Detection rate (other chromosomal anomalies)20/35 (57%)25/35 (71%)0.32
Terminations done for DS39/19 796 (0.20%)24/19 776 (0.12%)0.08
Fetal loss rate in fetuses with DS (terminations and miscarriages)45/19 796 (0.23%)27/19 776 (0.14%)0.04
Rate of invasive tests (for karyotyping)1593/19 796 (8%)2118/19 776 (0.14%)< 0.001
Spontaneous fetal loss rate after invasive tests in normal fetuses14/1507 (0.9%)15/2041 (0.7%)0.58
No. of invasive tests per one case of DS detected (< 22 weeks) (if karyotyping performed only for defined policy)1689

Of the 43 cases of DS, diagnosis was made in one case by amniocentesis at < 22 weeks but pregnancy continued, and in other diagnosis made at 35 weeks – leaving 41 cases for calculating DR.

From: 9, Screening for fetal anomalies

Cover of Antenatal Care
Antenatal Care: Routine Care for the Healthy Pregnant Woman.
NICE Clinical Guidelines, No. 62.
National Collaborating Centre for Women's and Children's Health (UK).
London: RCOG Press; 2008 Mar.
Copyright © 2008, National Collaborating Centre for Women’s and Children’s Health.

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