Prediction of adverse perinatal outcome by maternal serum screening for Down syndrome in an Asian population

Objective: To investigate the association between adverse perinatal outcomes and abnormal elevations of serum marker levels (alpha-fetoprotein [AFP] and free β-hCG) or a false-positive screen for Down syndrome. Methods: Pregnancy outcome information was available for 5885 Taiwanese women under 33 years of age who had second-trimester maternal serum screening for Down syndrome, using AFP and free β-hCG, and delivered a chromosomally normal fetus. Those with AFP at least 2.0 multiples of the median (MoM), free β- hCG at least 2.5 MoM, or a false-positive screen (risk ratio at least 1:270) were identified, and the risk for adverse perinatal outcome was assessed. Results: A serum AFP level at least 2.0 MoM (n = 176, 3.0%) was significantly associated with the occurrence of preterm delivery, low Apgar scores, small- for-gestational-age infants, low birth weight or very low birth weight, fetal death, premature rupture of membranes, oligohydramnios, and a higher incidence of perinatal mortality. A serum free β-hCG level at least 2.5 MoM (n = 416, 7.1%) was significantly associated with low birth weight, an abnormally adherent placenta, and the occurrence of meconium-stained amniotic fluid. A higher incidence of fetal structural anomalies other than neural tube or abdominal wall defects, large-for-gestational-age infants, and postpartum hemorrhage was observed for a calculated risk of at least 1:270 (n = 311, 5.3%) independent of the other biochemical markers. Conclusion: Asian women with unexplained elevations of serum AFP or free β-hCG, or a false- positive screen for Down syndrome are at increased risk for various adverse perinatal outcomes. Careful fetal ultrasound examination and thoughtful strategy for perinatal management are warranted for these patients.