Objective: To assess the relative risk of an adverse pregnancy outcome in women whose multiple-marker screening (maternal serum alpha-fetoprotein [MSAFP], unconjugated estriol [E3], and hCG levels, and age) indicating an increased risk for Down syndrome (more than 1:250) was not confirmed by amniocentesis.
Methods: Fifty-eight women with false-positive screens for Down syndrome were matched with a control group of 116 women whose screens indicated a risk for Down syndrome of less than 1:250. The risk for adverse pregnancy outcome was compared for the two groups, and the roles of MSAFP, unconjugated E3, and hCG as predictors of adverse pregnancy outcome were determined.
Results: Women with false-positive screens for Down syndrome were significantly different from their matched controls in the incidence of preterm delivery (20.6 versus 8.6%, respectively), preeclampsia (6.9 versus 0%), small for gestational age newborns (5.2 versus 0%), and fetal demise after 20 weeks' gestation (5.2 versus 0%). An adverse outcome occurred in 19 of 58 pregnancies (32.8%) in the study group and in 14 of 116 matched control pregnancies (12%) (odds ratio [OR] 3.5, 95% confidence interval [CI] 1.6-7.8; P < .01). Unconjugated E3 of 0.75 multiples of the mean (MoM) or less was significantly associated with adverse pregnancy outcome after controlling for the effects of MSAFP and hCG (OR 2.5, 95% CI 1.13-5.55; P < .02).
Conclusion: One in three women with a false-positive screen for Down syndrome may experience an adverse pregnancy outcome. In this study, unconjugated E3 of 0.75 MoM or less appeared to be a better predictor of adverse pregnancy outcome than were MSAFP and hCG levels.