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Risk factors for postpartum hemorrhage: can we explain the recent temporal increase?
Michael S Kramer1, Mourad Dahhou2, Danielle Vallerand3
1Department of Pediatrics, Faculty of Medicine, McGill University, Montreal QC; Department of Epidemiology, Biostatistics and Occupational Health, Faculty of Medicine, McGill University, Montreal QC.
Journal of Obstetrics and Gynaecology Canada : JOGC = Journal D'Obstetrique Et Gynecologie Du Canada : JOGC
|August 18, 2011
Summary
Increased rates of postpartum hemorrhage (PPH) are linked to labor induction, augmentation, and prior Cesarean sections. These factors, rising over time, largely explain the increasing incidence of PPH in industrialized nations.
Area of Science:
- Obstetrics and Gynecology
- Maternal-Fetal Medicine
- Epidemiology
Background:
- Postpartum hemorrhage (PPH) remains a significant cause of maternal morbidity and mortality worldwide.
- Recent reports indicate a rising incidence of PPH in industrialized countries, prompting investigation into contributing factors.
- Understanding the evolving risk factors is crucial for effective prevention and management strategies.
Purpose of the Study:
- To identify key risk factors associated with postpartum hemorrhage (PPH).
- To determine the extent to which changes in identified risk factors explain the increasing PPH rates observed in recent years.
- To provide evidence-based insights for clinical practice and public health initiatives.
Main Methods:
- A hospital-based cohort study was conducted, analyzing data from 103,726 deliveries between 1978 and 2007.
- Adjusted odds ratios were calculated to assess associations between various factors and PPH (defined as blood loss > 500 mL for vaginal, > 1000 mL for Cesarean).
- Severe PPH (blood loss ≥ 1500 mL) and PPH requiring transfusion or hysterectomy were also examined.
Main Results:
- Major independent risk factors for PPH included primiparity, prior Cesarean section, placenta previa, marginal cord insertion, transverse lie, labor induction/augmentation, trauma, preterm birth (<32 weeks), and high birth weight (≥4500 g).
- While PPH rates initially increased over the study period, this trend was attenuated after accounting for maternal age, parity, prior Cesarean section, labor induction/augmentation, and placental abnormalities.
- The rise in prior Cesarean sections and labor augmentation significantly contributed to the observed increase in PPH incidence.
Conclusions:
- Labor induction, augmentation, and prior Cesarean section are strongly linked to PPH risk.
- Increases in these specific interventions over the study period largely account for the rising incidence of postpartum hemorrhage.
- These findings highlight the need to re-evaluate obstetric practices and their impact on PPH rates.
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