A Swedish register-based study exploring primary postpartum hemorrhage in 405 936 full term vaginal births between 2005 and 2015

Abstract

Objective: To explore diagnoses of postpartum haemorrhage following vaginal birth, in relation to socio-demographic and obstetrical data from women who gave birth at term, in Sweden, during the years 2005-2015.

Study design: A register-based cohort study was carried out, describing and comparing socio-demographic variables, obstetric variables and infant variables in 52 367 cases of diagnosed postpartum haemorrhage compared to 353 569 controls without a postpartum haemorrhage diagnosis. Postpartum hemorrhage was identified in The Swedish Medical Birth Register by ICD-10 code O72. Variables for maternal characteristics were dichotomized and used to calculate odds ratios to find possible explanatory variables for postpartum haemorrhage.

Results: Between 2005 and 2015 there was no statistically significant decrease in diagnoses of postpartum haemorrhage after vaginal birth at term. Primiparity was associated with the highest risk and women birthing their fifth or subsequent child were associated with the lowest risk of postpartum hemorrhage. Increased maternal age (> 35 years) and/or obesity (BMI > 30) were associated with higher odds of postpartum haemorrhage. The risk of postpartum hemorrhage was 55 % higher when vaginal birth followed induction as compared to vaginal birth after spontaneous onset. Some of the factors known to be associated with postpartum haemorrhage were poorly documented in The Swedish Medical Birth Register.

Conclusions: Birthing women in a Swedish contemporary setting are, despite efforts to improve care, still at risk of birth being complicated by postpartum haemorrhage. Primiparity, increasing maternal age and/or obesity are found to provoke an increased risk and the reasons for these findings need to be further investigated. However, grand multi-parity did not increase the risk for postpartum hemorrhage. Codes for diagnoses require correct documentation in the birth records: only when local statistics are sound and correctly reported can intrapartum care be improved, and the incidence of postpartum haemorrhage reduced.

Keywords: Cohort study; Morbidity; Outcomes; Postpartum haemorrhage; Swedish Medical Birth Register; Vaginal births.