Risk factors for preterm delivery in women with placenta praevia and antepartum haemorrhage: retrospective study.

OBJECTIVE To identify risk factors for preterm delivery in women with placenta praevia and antepartum haemorrhage. DESIGN Retrospective study. SETTING Regional obstetric unit, Hong Kong. SUBJECTS AND METHODS Women delivered at Princess Margaret Hospital between 1 January 1990 and 31 December 1997. Possible risk factors for preterm delivery among women with placenta praevia and antepartum haemorrhage including onset, pattern, and severity of vaginal bleeding; presence of uterine contractions on admission; and type of placenta were assessed. RESULTS Three risk factors for preterm delivery were identified from univariate analysis. These included second trimester vaginal bleeding (odds ratio=4.19; 95% confidence interval, 1.29-13.66), the presence of uterine contractions on admission (odds ratio=4.00; 95% confidence interval, 1.57-10.19), and a haemoglobin decrease of more than 20 g/L (odds ratio=3.00; 95% confidence interval, 1.00-9.04). Using the logistic regression model, second trimester vaginal bleeding and the presence of uterine contractions were found to be independent risk factors for delivery before 36 weeks. CONCLUSION Preterm delivery is increased in women with placenta praevia and antepartum haemorrhage who have second trimester vaginal bleeding or the presence of uterine contractions. This high-risk group may benefit from close in-patient monitoring and more aggressive management.