Better labour epidural analgesia was associated with more intrapartum fever

Design

Multicentre prospective observational study

Population

952 nulliparous women at term with labour epidural analgesia

Primary outcome

Intrapartum hyperthermia (≥38°C)

Effect

13% febrile; time-weighted average pain OR 1.64 (1.40–1.91) per point lower

This multicentre prospective study followed 952 nulliparous women at term with a singleton cephalic pregnancy who had an epidural for labour, recording pain scores from before the block until delivery of the placenta.

Intrapartum fever of 38°C or more occurred in 13%. After adjustment, lower pain throughout labour was associated with higher odds of fever on every measure used (time-weighted average pain: OR 1.64 per point lower, 95% CI 1.40 to 1.91). Women whose average pain stayed at 3 or below had several-fold higher odds of fever than those with more pain.

The authors' explanation is that a denser, more extensive sympathetic block impairs sweating. Whatever the mechanism, the finding helps explain why some women with excellent epidurals become febrile without infection. It is not a reason to aim for worse analgesia, but it does inform how an isolated fever in a comfortable woman is interpreted.

• Expect some women with very effective epidurals to develop fever without infection.
• Still assess every intrapartum fever for chorioamnionitis and sepsis — this finding does not exclude them.
• Record temperature regularly once the epidural is sited, especially in long labours.
• Do not lighten an effective block to prevent fever; this study does not support that.

Why it matters

It links epidural-related fever to block quality, which helps interpret fever in otherwise well women.

Don't overread it

Observational — it does not show that dense blocks cause fever, or that fever in these women is harmless.

The statistics, in plain English

An odds ratio of 1.64 per point means each point lower on the pain score was associated with about 64% higher odds of fever. The very high odds ratios at the thresholds (6 to 13) come with wide intervals and should not be read as precise.

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