Is There an Increase of Postpartum Hemorrhage, and Is Severe Hemorrhage Associated With More Frequent Use of Obstetric Interventions?

Postpartum hemorrhage is a major complication associated with pregnancy and delivery and is a leading cause of maternal morbidity and mortality. A number of recent studies have reported an increasing incidence of severe postpartum hemorrhage. It has been suggested that the increased frequency may be related to higher rates of obstetric intervention, including cesarean section, induction of labor, and labor augmentation. This retrospective cohort study evaluated changes in postpartum hemorrhage over a 10-year period between 1998 and 2007 at a secondary referral center in Norway, and examined factors possibly associated with the occurrence of severe postpartum hemorrhage. Study subjects were an unselected population of 41,365 women between 23 and 43 weeks of gestation who delivered an infant with a birthweight of >300 g. Pregnancy and delivery data were collected prospectively and recorded in a computerized database; the analyses were performed retrospectively. During the 10-year study period, changes in the incidence of severe postpartum hemorrhage (defined as estimated blood loss of more than 1000 mL), the mean volume of postpartum hemorrhage, and related factors were assessed. The primary study outcome was the frequency of severe postpartum hemorrhage and interventions. Multivariable logistic regression analysis was used to adjust for possible confounding factors associated with severe hemorrhage. Although the overall frequency of postpartum hemorrhage remained stable during the study period, the incidence of severe postpartum hemorrhage increased. Compared with vaginal delivery, the incidence of severe hemorrhage after delivery by cesarean was more than double (5.9%; 95% confidence interval, 5.3–6.6 vs. 2.8%; 95% confidence interval, 2.6–2.9). After cesarean section, the strongest associations with severe hemorrhage were found for twin deliveries (adjusted odds ratio [aOR,] 3.7) and general anesthesia [aOR, 3.0]); both P < 0.01). After vaginal deliveries, the most important factors associated with severe hemorrhage were twin deliveries (aOR, 6.8), retained placenta (aOR, 3.9), and induction of labor (aOR, 2.2) (all P < 0.01). During the study period, the frequency of obstetric interventions increased: inductions of labor increased from 14.3% to15.8%, augmentation of labor from 5.8% to 29.3%, elective cesarean sections from 2.4% to 4.9%, emergency cesarean sections from 5.5% to 8.9%, and operative vaginal delivery from 9.3% to 12.5%. The findings show an increase in the incidence of severe postpartum hemorrhage between 1998 and 2007 that occurred along with more frequent use of obstetric interventions.