Towards informed decisions about prenatal testing: A review

There are now several well-documented psychological problems associated with prenatal testing programmes. These include poor understanding of tests undergone or declined, anxiety following false positive results, and false reassurance in those receiving negative test results. There is, as yet, little evidence concerning how to provide services to circumvent these. The focus of this review is upon just one of these problems: how best to inform women about prenatal testing and their reproductive options following the diagnosis of a fetal abnormality. Possible methods of improving informed decision-making either about whether to undergo testing or whether to terminate an affected pregnancy are described drawing upon research from antenatal and other health care areas. Future challenges for clinical practice and research in this area concern the range of conditions and predispositions for which prenatal testing with the option of termination should be offered.     

The variation of risk estimates through pregnancy in second trimester maternal serum screening for Down syndrome

The variation of risk estimates in second trimester maternal serum screening for Down's syndrome has been shown to be considerable in quality control schemes, i.e. UKNEQAS. We studied the biological variation of risk estimates in 16 women through pregnancy. The maternal serum markers alpha-fetoprotein (AFP), human chorionic gonadotrophin (hCG), unconjugated estriol (uE3) and β-hCG were determined six times during late first to late second trimester, and the associated likelihood ratios for Down syndrome were calculated. The interpersonal variation of markers, as well as that of the likelihood ratio, was much greater than the intrapersonal variation. The average intrapersonal standard deviation (SD) of the triple test log likelihood ratio was 0.2291, corresponding to a central 95-percentile interval 0.36–2.81 of the likelihood ratio. The interpersonal SD of the log likelihood ratio was 0.5482, corresponding to a central 95-percentile interval 0.08–11.87 of the likelihood ratio. The large difference between the intra- and interpersonal variation makes it unlikely that biological variation through pregnancy is a major contributor to the variation of risk estimates obtained several times in the same pregnancy. Rather, improvements in analytical quality and laboratory management must be expected to result in reduced variation and, in consequence, better performance of screening. Copyright © 2002 John Wiley & Sons, Ltd.