A variety of factors predispose to puerperal infection and subsequent pyrexia. They can be broadly subdivided into antepartum and postpartum groups.

Antepartum factors include:

• duration of labour
• duration of membrane rupture before delivery
• the number of cervical examinations
• sexual intercourse Intrapartum factors include:
• iatrogenic bacterial contamination during examination, manipulation or instrumentation
• trauma, eg caesarian section, lacerations
• haemorrhage: consequent haematomas act as a infective focus

For unknown reasons, women of lower socioeconomic class are also more susceptible to infection.