Objective: To identify risk factors for immediate postpartum hemorrhage after vaginal delivery in a South American population.
Methods: This was a prospective cohort study including all vaginal births (N=11,323) between October and December 2003 and October and December 2005 from 24 maternity units in two South American countries (Argentina and Uruguay). Blood loss was measured in all births using a calibrated receptacle. Moderate postpartum hemorrhage and severe postpartum hemorrhage were defined as blood loss of at least 500 mL and at least 1,000 mL, respectively.
Results: Moderate and severe postpartum hemorrhage occurred in 10.8% and 1.9% of deliveries, respectively. The risk factors more strongly associated and the incidence of moderate postpartum hemorrhage in women with each of these factors were: retained placenta (33.3%) (adjusted odds ratio [OR] 6.02, 95% confidence interval [CI] 3.50-10.36), multiple pregnancy (20.9%) (adjusted OR 4.67, CI 2.41-9.05), macrosomia (18.6%) (adjusted OR 2.36, CI 1.93-2.88), episiotomy (16.2%) (adjusted OR 1.70, CI 1.15-2.50), and need for perineal suture (15.0%) (adjusted OR 1.66, CI 1.11-2.49). Active management of the third stage of labor, multiparity, and low birth weight were found to be protective factors. Severe postpartum hemorrhage was associated with retained placenta (17.1%) (adjusted OR 16.04, CI 7.15-35.99), multiple pregnancy (4.7%) (adjusted OR 4.34, CI 1.46-12.87), macrosomia (4.9%) (adjusted OR 3.48, CI 2.27-5.36), induced labor (3.5%) (adjusted OR 2.00, CI 1.30-3.09), and need for perineal suture (2.5%) (adjusted OR 2.50, CI 1.87-3.36).
Conclusion: Many of the risk factors for immediate postpartum hemorrhage in this South American population are related to complications of the second and third stage of labor.
Level of evidence: II.