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UBC Theses and Dissertations

Epidemiologic investigation of an increase in postpartum hemorrhage Mehrabadi, Azar


Increases in postpartum hemorrhage have been reported in several high income countries between 1991 and 2004. The purpose of this thesis was to investigate possible causes of recent increases in postpartum hemorrhage. Data sources included a population-based database of deliveries in British Columbia, Canada, between 2000 and 2009 (n=371,193), and a hospitalization database of deliveries in Canada (excluding Quebec) between 2003 and 2010 (n=2,193,425). Postpartum hemorrhage was defined as a blood loss of ≥500 mL for a vaginal delivery or ≥1000 mL for cesarean delivery or as a diagnosis noted by a health care provider. The influence of changes in risk factors on temporal trends in postpartum hemorrhage was studied using logistic regression. There was a significant increase in atonic postpartum hemorrhage in British Columbia from 4.8% in 2001 to 6.3% in 2009 (34% increase, 95% confidence interval [CI] 26-42%). This increase was not be explained by changes in the maternal, fetal and obstetric factors studied, including previously understudied factors such as maternal pre-pregnancy body mass index and labour augmentation with oxytocin. In Canada, rates of postpartum hemorrhage increased from 5.1% in 2003 to 6.2% in 2010 (22% increase, 95% CI 20% to 25%), driven by an increase in atonic postpartum hemorrhage. Placenta accreta was responsible for only a negligible fraction of postpartum hemorrhage. Temporal trends in severe postpartum hemorrhage in Canada showed a similar pattern; postpartum hemorrhage with blood transfusion increased from 36.7 in 2003 to 50.4 per 10,000 deliveries in 2010, while postpartum hemorrhage with hysterectomy increased from 4.9 to 5.8 per 10,000 deliveries over the same period. The temporal increase in postpartum hemorrhage did not explain a concurrent rise in obstetric acute renal failure in Canada. The increase in obstetric acute renal failure was restricted to women with hypertensive disorders of pregnancy. In summary, postpartum hemorrhage and severe postpartum hemorrhage continued to increase in Canada in recent years, and the maternal, fetal and obstetric factors studied did not explain the rise. Further studies are required to identify the role of other risk factors that may explain the observed increase in postpartum hemorrhage.

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