Purpose: The aim of this study was to determine the influence of various factors on preterm labor symptoms (PLS) and preterm birth (PB). Methods: This prospective cohort study included 193 women in the second stage of pregnancy. Multiple characteristics including body mass index(BMI), smoking, and pregnancy complications were collected through a self-report questionnaire. Pregnancy stress and PLS were each measuredwith a related scale. Cervical length and birth outcome were evaluated from medical charts. Multiple regression was used to predict PLSand logistic regression was used to predict PB. Results: Multiple regression showed smoking experience, pregnancy complications and pregnancyspecific stress were predictors of PLS and accounted for 19.2% of the total variation. Logistic regression showed predictors of PB to be twins(OR=13.68, CI=3.72~50.33, pqqqlt;.001), shorter cervix (qqqlt;25mm) (OR=5.63, CI=1.29~24.54, pqqqlt;.05), BMI qqqgt;25 (kg/m2) (OR=3.50, CI=1.35~9.04, pqqqlt;.01)and a previous PB (OR=4.15, CI=1.07~16.03, pqqqlt;.05). Conclusion: The results of this study show that the multiple factors affect stage II pregnantwomen can result in PLS or PB. And preterm labor may predict PB. These findings highlight differences in predicting variables for pretrm laborand for PB. Future research is needed to develop a screening tool to predict the risk of preterm birth in pregnant women.