UKMidSS update

Women who have experienced a postpartum haemorrhage (PPH) ‘requiring treatment or transfusion’ are typically advised to plan birth in obstetric-led settings in subsequent pregnancies. This study aimed to use the UK Midwifery Study System (UKMidSS), a system similar to the UK Obstetric Surveillance System (UKOSS) but which operates in midwifery-led units, to describe outcomes in women admitted for labour care to Alongside Midwifery Units (AMUs) following a previous PPH. It also sought to compare outcomes with other multiparous women admitted to the same AMUs and explore risk factors for recurrence. All 123 AMUs in the UK participated in the study. Between August 2018 and April 2019 there were 1866 women admitted to an AMU with a confirmed previous PPH, who were compared with 1850 multiparous women admitted to the same units. Women who experienced a previous PPH were significantly more likely than comparison women to: have a PPH requiring transfer to obstetric care (4.2% versus 2.4%, adjusted risk ratio [aRR] = 1.65, 95% CI = 1.14–2.38), be transferred to obstetric care for any reason (17.8% versus 11.9%; aRR = 1.41; 95% CI = 1.09– 1.83) and have any PPH ≥500 ml (22.7% versus 11.1%, aRR = 1.86, 95% CI = 1.49–2.32). Among women with a previous PPH, previous blood loss >1500 ml, uterotonics for previous PPH, caesarean associated with previous PPH, gestation at admission and higher infant birth weight were independent risk factors for PPH. This study showed that women considering birth in an AMU after a previous PPH should be advised that they are at increased risk of experiencing a subsequent PPH requiring transfer to obstetric care, compared with other multiparous women who have not had a PPH. However, the absolute risk of a subsequent PPH in this group is low and comparable to the overall risk of having a PPH among women having a spontaneous vaginal birth in England.