Fetal loss in Down syndrome pregnancies

✍ Scribed by Rosalinde Snijders

• Publisher: John Wiley and Sons
• Year: 1999
• Tongue: English
• Weight: 47 KB
• Volume: 19
• Category: Article
• ISSN: 0197-3851
• DOI: 10.1002/(sici)1097-0223(199912)19:12<1180::aid-pd732>3.0.co;2-v

✦ Synopsis

Fetal Loss in Down Syndrome Pregnancies

In a recent paper, Morris et al. (1999) deduce that about 43 per cent of Down syndrome pregnancies are destined to result in spontaneous loss between the first trimester and term. This relatively high estimate for the rate of loss is derived on the basis of data from two studies that both provide an estimate of 31 per cent (Halliday et al., 1995;Morris et al., 1999), and a third study that presents a much higher estimate of 48 per cent (Mackintosh et al., 1995). It is important to stress that the authors failed to identify an important factor that may at least partly explain the difference in results. Comparison of gestational age in the three data sets reveals that the study with the highest loss rate included pregnancies examined at relatively early gestational ages (8-12 weeks' gestation). In a recent paper, Snijders et al. (1999) stratified loss rates by gestational age and demonstrated that the loss rate decreases throughout the first trimester (Table 1). On the basis of these data it is estimated that 30 per cent, rather than 43 per cent, of pregnancies with Down syndrome are destined to result in spontaneous miscarriage between first trimester testing (which is done at about 12 weeks of gestation) and term. Studies and models that apply higher spontaneous loss rates as proposed by Hackshaw et al. (1996), Morris et al. (1999) and Wald et al. (1999) will underestimate the efficacy of first trimester screening.