Preterm Delivery Prediction by the Measurement of Cervicovaginal Beta Human Chorionic Gonadotropin(β-hCG)

Preterm delivery is the main cause of perinatal morbidity and mortality throughout the world. Many complications such as neonatal intraventricular hemorrhage, cerebral palsy and high cost have increased the importance of preterm delivery therefore, it is important to detect high risk women early in pregnancy in order to prevent this problem. All of the methods used for preterm delivery prediction have not been successful. The main purpose of this study was to determine the accuracy of cervicovaginal beta human chorionic gonadotropin(β-hCG) levels for preterm delivery prediction. This study was undertaken on 354 pregnant women with gestational age(GA) of 24-28 weeks attending health centers of Sari in Iran between 2000 and 2004. Provided samples from cervicovaginal secretions were sent to laboratory and β-hCG titers were measured by the ELISA method and were documented in relative sheets. Then, all pregnant women were followed until their deliveries. GA at delivery was determined in the first post partum visit. Pregnancy women were called in case they did not come to the health centers and after referring, necessary information was acquired and relative sheets were completed. For statistical analysis, a cut off value of 30 mIU/ml for β-hCG titers was considered and (preterm or term) sensitivity, specificity, positive and negative predictive values of this test for preterm delivery prediction were calculated in the post partum visit after recognizing the time of delivery. Out of 354 persons 68(19.2%) pregnant women had delivery before 37th week of gestation. The β-hCG levels had a range of 0-196 mIU/ml with a mean of 37.5. 75% of subjects in preterm delivery group and 10.5% of women in term delivery group had a cervicovaginal β-hCG level higher than 30 mIU/ml. Sensitivity, specificity, positive and negative predictive values of β-hCG for preterm delivery prediction were 75%,89.5%, 63.96% and 93.77%, respectively. The high negative predictive value of cervicovaginal β-HCG for preterm delivery prediction(particularly in high risk women) may limit unnecessary hospitalization and potentially harmful manipulations.