BACKGROUND AND PURPOSE:

• Data is limited regarding
  • PPH and impact of family history
  • Extent that birthweight influences PPH recurrence between relatives
• Linde et al. (Acta Obstet Gynecol Scand, 2021) investigated family aggregation of PPH and how birthweight influences these effects

METHODS:

• Population-based cohort study
  • Data derived from
    • The Medical Birth Registry of Norway
    • Statistics Norway
    •  Central Population Registry of Norway
• Population
  • Born in Norway and their family members
  • Using the above databases, population-based pedigrees could be constructed
  • Individuals identified as either newborns, parents, grandparents and full or half-siblings
• Exposures
  • PPH in family member
• Study design
  • Multilevel logistic regression was used to calculate odds ratios (OR) with 95% CI
• Primary outcome
  • PPH in newborn birth

RESULTS:

• Mother-offspring pairs: 1,002,687 | Father-offspring pairs: 841,164 | Both parent-offspring pairs: 761,011
• Births of family members that involved PPH were associated with an increased odds of PPH in the offspring’s birth
  • When mother’s birth involved PPH: 1.44 (95% CI 1.39 to 1.49)
  • When father’s birth involved PPH: 1.12 (95% CI, 1.08 to 1.16)
• Effects more pronounced with severe PPH
• Recurrence between siblings was highest between full sisters
  • OR 1.47 (95% CI 1.41 to 1.52)
• Highest recurrence occurred, in descending order, between
  • Maternal half-sisters
  • Paternal half-sisters
  • Partners of full brothers
• The following factors contributed to total number of PPH cases
  • Family history of PPH: Accounted for ≤5% of the total number of PPH cases
  • Family history of birthweight of >4000 g: 15% of the total number of PPH cases

CONCLUSION:

• A history of PPH in relatives was associated with an increased odds of PPH recurrence
  • This increased risk was greater in when the relative was more closely related to the focal birth
  • Recurrence was highest through the maternal line
• The authors state

Women with a family history of PPH had an increased risk of PPH in a dose–response pattern consistent with the anticipated proportion of shared genes in relatives

This risk was strongly modified by current birthweight

On a population level, a history of PPH in relatives accounted for a low number of PPH cases, whereas the current birthweight accounted for a more significant number of PPH cases

Learn More – Primary Sources:

Recurrence of postpartum hemorrhage in relatives: A population-based cohort study

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