Excessive bleeding after childbirth, known as postpartum haemorrhage (PPH), can turn an uncomplicated birth into a catastrophe. Each year, PPH occurs in an estimated 27 million women worldwide-17 million after vaginal birth and 10 million during or after caesarean birth. An estimated 43 000 women die from PPH annually, translating to a death every 12 min. The pooled prevalence of PPH at vaginal birth is 12·6% (95% CI 10·1-15·2) and at caesarean birth 30·9% (95% credible interval 24·9-37·6), based on the conventional definition of PPH. Common causes of PPH are uterine atony, genital tract trauma, retained placenta, abnormal placentation, and coagulopathy. Risk factors include caesarean birth, multiple pregnancy, anaemia, high maternal BMI, previous PPH, female genital mutilation, sepsis, pre-eclampsia, macrosomia, and inadequate antenatal care. In addition to being the leading cause of maternal mortality worldwide, the consequences of PPH include serious morbidities such as severe anaemia, hysterectomy, organ failure, and long-term psychological trauma. The global economic burden of PPH is estimated at US$10·4 billion (95% credible interval $9·8-13·2 billion) annually, consisting of $3·6 billion ($3·2-6·2 billion) for health systems and $6·8 billion ($6·2-7·5 billion) for societies. Based on a rigorous review of the evidence, WHO has recently redefined PPH as objectively measured blood loss of at least 300 mL plus an abnormal haemodynamic sign, or objectively measured blood loss of at least 500 mL, whichever occurs first. This new definition prioritises early PPH diagnosis and treatment to avert life-threatening maternal outcomes. Comprehensive efforts to address missed opportunities in the prevention, diagnosis, and treatment of PPH are needed to improve outcomes. These efforts include addressing the unmet need for contraception, mitigating modifiable risks such as anaemia, avoiding caesarean sections that are not medically indicated, using effective single uterotonic prophylaxis for all births and combination prophylaxis for women at high risk of PPH, ensuring accurate and objective measurement of blood loss for early PPH diagnosis, and promptly implementing treatment with an evidence-based bundle. The PPH Roadmap (2023-30) provides a global framework for action.