Participation in maternal serum screening for Down syndrome, neural tube defects, and trisomy 18 following screen-positive results in a previous pregnancy

Objective To determine whether women who have had a positive serum screening result for Down syndrome or neural tube defect in 1 pregnancy have a lower rate of participation in screening in their next pregnancy. Setting A triple-marker screening program at a university hospital. Methods Pregnancy and screening information was collected from laboratory and hospital databases to compare subsequent screening participation of women who were screen-negative and screen-positive for the risk of a fetus with Down syndrome or a neural tube defect. Results In an age-matched comparison, 108 women who had a previous screen-positive result were significantly less likely than 108 women who were screen-negative to participate in maternal serum screening in their next pregnancy. When examined according to the type of screen-positive result, the effect was significant for both those who were screen-positive for Down syndrome and those who were screen-positive for neural tube defect. The degree of risk in screen-positive women did not significantly affect their participation in screening in the next pregnancy. Conclusions Anxiety related to a screen-positive result probably causes decreased participation in maternal serum screening in the next pregnancy. Reducing the screen-positive rate in prenatal serum screening would alleviate maternal anxiety and would probably lead to more stable participation.Maternal serum screening, performed at 15 to 20 weeks of pregnancy, is commonly used in the prenatal detection of open neural tube defects, Down syndrome, and trisomy 18. By its nature as a screening test, maternal serum screening cannot determine with certainty if the baby is affected with a fetal anomaly. Most women who receive screening results indicating a high risk (screen-positive) have unaffected babies (false-positive), and some receiving results indicating a low risk (screen-negative) have affected babies (false-negative). Risk cutoffs are chosen to optimize the detection rate while maintaining a relatively low (5%-10%) false-positive rate.Farrant first reported that false-positive results were associated with higher levels of maternal anxiety.¹ All subsequent studies of women who received false-positive results, indicating an increased risk of Down syndrome or neural tube defects, have confirmed this observation.^{2,3,4,5,6,7,8,9} Heightened anxiety was found to persist in screen-positive patients even after their initial positive results were shown to be false.^{2, 10} It is not surprising, then, that women with false-positive results, compared with those with true-negative results, were more opposed to maternal serum screening^{11, 12} and were less likely to say that they would choose maternal serum screening in a future pregnancy.^{11, 13} However, whether this negative attitude translates into reduced screening participation in a future pregnancy has not yet been reported.The purpose of this study was to determine whether women who have had a positive serum screening result in 1 pregnancy have a lower rate of participation in screening in their next pregnancy than women who were screen-negative in their previous pregnancy. We also examined whether it made a difference if women were screen-positive for Down syndrome or neural tube defect or whether the degree of increased risk made a difference in subsequent screening participation. Finally, we asked if screen-positive women who declined serum screening in their subsequent pregnancy chose other forms of prenatal testing instead, such as amniocentesis or ultrasound examination.