Analytical Comparison of Pregnancy-Associated Plasma Protein-A (PAPP-A) Immunoassays for Biochemical Determination of Gestational Age

PAPP-A as a screening tool for assessment of gestational age before medication abortion in an intended-use population

Introduction: Prior studies indicate that PAPP-A could serve as a marker of gestational age (GA) with the potential to determine eligibility for medication abortion. The authors validated the relationship between PAPP-A and GA in an actual-use population. Materials & methods: The authors collected blood samples, medical histories and ultrasound-determined GA from patients presenting for abortion services. They measured PAPP-A using two immunoassays and assessed diagnostic accuracy for predicting GA ≥71 days. Results: The Ansh Labs and R&D Systems immunoassays produced an area under the ROC curve of 0.982 (95% CI: 0.958-0.994) and 0.986 (95% CI: 0.963-0.996), respectively, for predicting GA ≥71 days. Conclusion: This validation study in an intended-use population confirmed that PAPP-A has a strong ability to distinguish pregnancies above and below 71 days' gestation. Clinical trial registration: NCT04232189 (ClinicalTrials.gov).