Second Trimester Serum Biomarker Screen for Fetal Aneuploidies as a Predictor of Preterm Delivery: A Population-Based Study.

OBJECTIVE: To determine the association between second-trimester serum Down syndrome screening (alpha-fetoprotein [AFP] free beta-human chorionic gonadotropin [b-hCG] unconjugated estriol [uE3]) and preterm birth and to create predictive models for preterm birth.

METHODS: Secondary analysis on a prospective database of pregnancies undergoing second-trimester screen with complete follow-up. The multiples of medians (MoM) of the biomarkers were compared between the group of term, preterm (< 37 weeks), early preterm (< 34 weeks), and very early preterm (< 32 weeks) delivery. Predictive models were developed based on adjusted MoMs and logistic regression and diagnostic performances in predicting preterm birth were determined.

RESULTS: Of 20,780 pregnancies, 1,554 (7.5), 363 (1.7), and 158 (0.8%) had preterm, early preterm, and very early preterm birth respectively. High levels of AFP and b-hCG but low levels of uE3 were significantly associated with higher rates of preterm, early preterm and very early preterm delivery. The predictive models had diagnostic performance in predicting preterm birth with the areas under the ROC curve of 0.688, 0.534, 0.599, and 0.718 for AFP, b-hCG, uE3, and combined biomarkers respectively.

CONCLUSION: The second trimester Down syndrome screening could also be used as a tool of risk identification of preterm birth in the same test, without extra-effort and extra-cost.