Background :  Evaluation of cervicovaginal fetal fibronectin was considered as one of the most predictive factor for preterm labor when it is 50 ng/ml. Also, Salivary estriol (E3) has the same predictive factor for preterm labor when it is over 2.1ng/ml. The last factor in this study was measurement of cervical length.
Objective: Assessing cervicovaginal fetal fibronectin and maternal Salivary estriol (E3) as biochemical markers, as well as transvaginal ultrasound in the prediction of preterm labor.
 Patients and Methods: The study included 150 pregnant women at gestational ages between 24 weeks and 34 weeks confirmed by sure history of last menstrual period and first trimestric ultrasound examination.The patients in this study were fulfilling the inclusion criteria, and were enlisted in a prospective clinical trial. As regard cervicovaginal fetal fibronectin, measure of it as Dacron swab was rotated in posterior fornix of the vagina or ectocervix and sent for assay of fetal fibronectin.
 Salivary estriol (E3) was collected from mouth after washing it, and stored till time of assay. Cervical length was evaluated by transvaginal ultrasound.
Results: There was a highly significant difference between women with positive and negative fibronectin regarding gestational age at delivery. Salivary estriol (E3) showed    a highly significant difference between women with positive and negative E3 regarding gestational age at delivery. Also, cervical length showed a highly significant difference between women with short and normal cervical length regarding gestational age at delivery. There was no significant effect for age, parity, presence of uterine contractions and uterine anomalies on the outcome of pregnancy .
Conclusion: Cervicovaginal fetal fibronectin, salivary estriol E3 and measurement  of cervical length were more helpful in prediction of preterm labor.