RESUMO
Objective: To explore the risk factors of primary postpartum hemorrhage (PPH) in pregnant women who delivered at Siriraj Hospital. Methods: The medical records of pregnant patients who delivered vaginally at Siriraj Hospital during January 1st to December 31st, 2005 were enrolled into 2 groups. The study group was singleton pregnancy with primary PPH and the control group was sandwich singleton pregnancies who delivered without PPH. The ratio between the study and the control group was 1:2. Baseline characteristics and obstetrics data of each group were collected. Descriptive statistics, independent sample t-test, odds ratio, 95% confidence interval and multiple linear regression analysis were used in this study. Results: A total number of 222 medical records were reviewed. The number of the patients in the study group and control group were 74 and 148, respectively. By multiple linear regression analysis, the data revealed that prolonged third stage of labor and pregnancy induced hypertension were the significant risk factors related to primary PPH (P <0.05, 95%CI 0.2-0.65 and 0.01-0.47, respectively). The three most common causes of primary PPH in the study group were uterine atony (77.03%), birth passage injury (24.32%) and retained pieces of placenta (20.27%), respectively. Conclusion: The significant risk factors of primary PPH in this study were prolonged third stage of labor and pregnancy induced hypertension. Uterine atony, birth passage injury and retained pieces of placenta were the next most common causes of primary PPH.