Background: Preterm delivery is one of the important problems in obstetrics and finding a way for its prediction and prevention has always been under investigation.

Materials and Methods: This study carried out to determine whether human chorionic gonadotropin (HCG) detected in cervicovaginal secretion of patients with symptoms suggestive of preterm labor is a predictor of preterm birth, and to determine the cut-off values for HCG in prediction of delivery before 37 weeks of pregnancy. 150 pregnant women with gestational age 24-34 weeks and diagnosis of preterm labor and intact membrane were enrolled to the study. The patients were allocated in two groups and HCG in cervicovaginal secretion was measured in all of them. The patients were followed until their delivery and were divided in two groups. Seventy one cases delivered after 37 weeks of pregnancy (term) and 79 before 37 weeks (preterm). The amount of HCG in cervicovaginal secretion of the two groups was compared.

Results: Mean concentration of HCG in cervicovaginal secretion in term group was 7.9 ± 34.1 miu/ml and in preterm group 61.12 ± 66.84 miu/ml which was statistically significant (p<0.001). A significant positive correlation was found between the cervical HCG concentration, gestational age at the time of sampling (p<0.01, r=0.2), cervical dilatation (p<0.001, r=0.54) and cervical effacement (p<0.001, r=0.43), and a significant negative correlation between the cervical HCG concentration, gestational age at the time of delivery (p<0.001, r=-0.4). The cut-off value for cervical HCG concentration, its sensitivity, specificity, positive and negative predictive values and accuracy for determination of delivery before 37 weeks of pregnancy were 9.5 miu/ml, 92.4% (95%CI= 83.6-96.9), 87.3% (95%CI= 76.8-93.7), 89%, 91.27% and 90%, respectively. However, these characteristics for HCG concentration of 10.5 miu/ml were 79.7% (95%CI =68.9-87.6), 93% (95%CI =83.7-97.4), 92.6%, 80.5% and 86% respectively, and for HCG concentration of 13.5 miu/ml were 73.4% (95%CI= 62.1-82.4), 98.6%(95%CI =93.1-99.9), 98.3%, 76.9% and 85.3% respectively.

Conclusion: Quantitative HCG concentration measurement from cervicovaginal secretions may be a useful predictor of preterm birth in symptomatic patients. This test has the advantage of low cost and wide availability.