Postpartum haemorrhage (PPH) is defined as blood loss of > 500 ml after a vaginal delivery and may be primary or secondary.

Primary postpartum haemorrhage

Primary PPH occurs within 24 hours. It affects around 5-7% of deliveries.

The causes of PPH are said to be the 4 Ts:

• Tone (uterine atony): the vast majority of cases
• Trauma (e.g. perineal tear)
• Tissue (retained placenta)
• Thrombin (e.g. clotting/bleeding disorder)

Risk factors for primary PPH include*:

• previous PPH
• prolonged labour
• pre-eclampsia
• increased maternal age
• polyhydramnios
• emergency Caesarean section
• placenta praevia, placenta accreta
• macrosomia
• the effect of parity on the risk of PPH is complicated. It was previously thought multiparity was a risk factor but more modern studies suggest nulliparity is actually a risk factor

Management

• PPH is a life-threatening emergency - senior members of staff should be involved immediately