Postpartum hemorrhage risk is driven by changes in blood composition through pregnancy

Area of Science:

• Obstetrics and Gynecology
• Hematology
• Reproductive Health

Background:

• Individual variations in blood cell counts during pregnancy are not well understood.
• These changes may influence pregnancy outcomes, particularly postpartum hemorrhage (PPH), a major cause of maternal mortality.

Purpose of the Study:

• To analyze individual differences in blood cell count trajectories throughout pregnancy.
• To determine the association between these blood count changes and the risk of postpartum hemorrhage.

Main Methods:

• Prospective cohort study of 4082 births at University Hospital, Lausanne, Switzerland (2009-2014).
• Statistical analysis of repeated measures data for complete blood count (CBC) parameters.
• Investigation of trimester-specific associations between CBC values and PPH incidence.

Main Results:

• Significant inter-individual differences were observed in the changes of mean corpuscular hemoglobin, mean corpuscular volume, mean platelet volume, platelet count, and red cell distribution width throughout pregnancy.
• Most CBC values exhibited trimester-specific associations with PPH risk.
• High platelet count, mean platelet volume, and erythrocyte levels in trimester 1 were associated with increased PPH risk, while high values in trimester 3 were associated with decreased risk.

Conclusions:

• Individual variability in blood cell count changes during pregnancy plays a crucial role in pregnancy outcomes.
• Monitoring blood count trends throughout gestation can improve the identification of women at higher risk for postpartum hemorrhage.
• This understanding aids in stratifying patients into appropriate risk groups for enhanced maternal care.