Adverse pregnancy outcome after a false-positive screen for Down syndrome using multiple markers.

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.