Evaluation of placental alpha microglobulin-1(PAMG1) accuracy for prediction of preterm delivery in women with the symptoms of spontaneous preterm labor; a comparison with cervical length and number of contractions

Introduction: Since the capacity of tertiary centers is limited, identifying women with the risk of preterm delivery is crucial amongst women who refer to hospitals with threatened preterm labor. Objective: The purpose of the present study was to evaluate the accuracy of the placental alpha microglobulin-1 (PAMG-1) test for identifying women who referred to hospitals with signs of spontaneous preterm labor and ultimately delivered within <= 48 h and <= 7 of testing and <= 37 weeks of gestation and its comparison with cervical length of Materials and methods: A prospective observational study was performed on women with the signs of spontaneous preterm labor. Placental alpha microglobulin-1 (PAMG-1) was evaluated in vaginal secretion. Cervical length (CL) and number of contractions were evaluated and recorded. The test to- spontaneous- delivery interval was documented. Sensitivity (SN), specificity (SP), accuracy rate of the PAMG-1, cervical length of <25 mm and number of contractions in prediction of spontaneous preterm delivery within <= 48 h, <= 7 days and preterm delivery (<= 37 weeks of gestation) were calculated. Results: One hundred eighty women finished the study. 44 women had positive PAMG-1 test and 58 women had cervical length of <25 mm. Women with a positive PAMG-1 were more likely to deliver within <= 48 h (p < .0001), <= 7 days (p < .0001), and before 37 weeks (p < .0001), compared to the women who had a negative test. For delivery within <= 48 h, <= 7 days and <= 37 weeks, specificity (SP) of the PAMG-1; was statistically higher than cervical length of <25 mm and contractions of 12-17/hr but not contractions of >= 18/hr. PAMG-1 showed a higher accuracy rate than cervical length of <25 mm, contractions of 12-17/hr and contractions of >= 18/hr for deliveries within <= 48 h (78.9, 55.3, 48.9, and 69.44%, respectively) and <= 7 days (76.1, 55.32, 55, and 65.56%, respectively). For deliveries before 37 weeks; the PAMG-1 test showed higher LR + than CL of <25 mm, contractions of 12-17/hr and contractions of >= 18/hr [10.24 (2.57-40.86), 2.01 (1.24-3.23), 1.30 (1.05-1.62), and 5.12 (1.24-21.11), respectively]. PPV for deliveries within <= 48 h and <= 7 days for PAMG-1 was greater than cervical length of <25 mm and number of contractions, however, NPV did not show a significant difference. Conclusion: PAMG-1 test showed a higher accuracy rate for prediction of delivery within <= 48 and <= 7 days in comparison with cervical length of <25 mm and number of contractions. Also, PAMG-1 test had a higher positive likelihood ratio for deliveries at <= 37 weeks. PPV for deliveries within <= 48 h and <= 7 days for PAMG-1 was greater than cervical length of <25 mm and number of contractions, however, NPV did not show a significant difference.