OC187: Results of the Swedish NUPP-study

To compare two routines of offering prenatal diagnosis: 1/fetal ultrasound examination (US) at 18 gestational weeks (gws) and information on the risk of fetal chromosomal anomaly on the basis of maternal age (late scan) 2/fetal US at 12 gws and information about the risk of fetal chromosomal anomaly on the basis of nuchal translucency (NT) (early scan). National multicenter study. 40 000 pregnant women were randomized to an early or late scan as described above. Ten dating formulas were tested in 363 singleton IVF pregnancies. The best dating formula was one not in current use (Selbing & Kjessler 1986). It underestimated gestational age by 0.4 days ± 1.87 in the early group and by 0.2 days ± 3.25 in the late group. 1000 women in each group underwent psychological testing and answered questionnaires. There was no difference between the groups with regard to the mother's worry about the baby. 91% of the women in both groups underwent a routine scan where at least one living fetus was found. More cases with Down syndrome (DS) were identified in the early group (55 vs 43). A diagnosis of DS was made prenatally in a living fetus < 22 gws in 76% (42/55) of the cases with DS in the early group vs. in 58% (25/43) in the late group. The corresponding rates for the early and late routine were 71% (39/55) and 49% (21/43). The rate of legal abortion for DS was higher in the early than in the late group (39 vs. 24; 0.2% vs. 0.1%), but the number of babies born with DS was only slightly different (13 vs.16). Detection of trisomies 18 and 13 and X0 was similar in the two groups. Fewer babies with isolated spina bifida were detected prenatally < 22 gws in the early scan group (4/11 vs. 5/9). Amniocentesis rates were 8% vs. 11%. The early routine was associated with a higher prenatal detection rate of DS and more legal terminations for DS, but the difference in babies born with DS was small. Amniocentesis rates were lower with the early routine.