Quantitative assessment of placental alpha macroglobulin‐1 for predicting impending preterm delivery in asymptomatic women with a short cervix

Aims Preterm delivery (PTD) is a leading cause of neonatal morbidity and mortality. Accurate prediction is crucial for optimizing clinical outcomes, particularly in women with a short cervix. Although fetal fibronectin (FFN) is widely used to predict PTD, placental alpha‐microglobulin‐1 (PAMG‐1) has gained attention for its potential to improve predictive accuracy. This study aimed to evaluate the utility of quantitative PAMG‐1 assessment for predicting impending PTD in asymptomatic women with a short cervix (≤25 mm) between 24 and 34 weeks of gestation. Methods This observational cohort study analyzed 212 cervicovaginal fluid samples from 77 patients (132 from 49 singleton and 80 from 28 twin pregnancies). PAMG‐1 and FFN levels were measured, and multivariate logistic regression was performed to evaluate their association with PTD risk. Results In singleton pregnancies, positive PAMG‐1 was independently associated with impending PTD, with odds ratios of 7.84 (95% confidence interval [CI], 2.02–30.50; p = 0.003) and 7.34 (95% CI, 2.75–19.60; p < 0.001) for PTD within 1 and 2 weeks, respectively. Quantitative PAMG‐1 showed a dose‐dependent relationship, with PTD risks increasing from 4.3% (<1000 pg/mL) to 50.0% (≥3000 pg/mL) within 1 week and from 10.0% to 90.0% for PTD within 2 weeks. In twin pregnancies, both PAMG‐1 and FFN showed limited predictive utility. Conclusions This study highlights the potential of PAMG‐1 quantification as a valuable tool for refining PTD risk stratification, particularly in singleton pregnancies. While further prospective multicenter validation is needed, these findings provide new clinical insights for improving PTD management.