Risk Factors for Secondary Postpartum Haemorrhage: Preliminary Data for a Longitudinal Prospective Cohort Study Involving Women Presenting to a Single Tertiary Women's Hospital

Background Secondary postpartum haemorrhage (PPH) complicates approximately 1% of pregnancies and can cause significant morbidity. Understanding predisposing factors may aid its prevention and management. Aims To identify and assess risk factors for presentation to the emergency department with secondary PPH, including factors associated with increased severity and need for surgical management or inpatient care. Materials and Methods In this prospective observational study, patients who presented to a metropolitan Melbourne women's hospital (‘Level 6’ maternity referral centre) with secondary PPH between 1/7/2020 and 31/12/2021 were eligible for recruitment. Prospective clinical and demographic data was collected at time of emergency presentation; antenatal and intrapartum information were collected by review of medical records. Antenatal, birth and postpartum variables of those identified as presenting with a secondary PPH were compared with control participants who birthed at the institution in the same period. Comparisons were made using chi‐square tests, independent sample t ‐tests and Mann–Whitney U tests as appropriate. Results 168 patients who experienced a secondary PPH were recruited and compared with 9491 controls. Factors associated with secondary PPH included younger maternal age ( p = 0.004), lower parity ( p = 0.013), higher plurality ( p < 0.001), being born in Australia ( p = 0.008), incomplete placenta and/or membranes ( p < 0.001), greater blood loss at birth ( p = 0.014) and infant formula feeding on discharge ( p = 0.019). Some of these factors, as well as others, were also associated with increased severity of secondary PPH, surgical management or inpatient care. Conclusions Secondary PPH is a significant problem with associated risk factors. Further research should look at preventative mechanisms for secondary PPH. Trial Registration Australian New Zealand Clinical Trials Registry registration number: ACTRN12622000039785