Intrauterine temperature during intrapartum amnioinfusion: a prospective observational study

Abstract

Objective: To determine the influence of routine intrapartum amnioinfusion (AI) on intrauterine temperature.

Design: Prospective observational study.

Setting: Maternity unit, Barnes Jewish Hospital, St Louis, MO, USA.

Sample: Forty women with singleton gestations and an indication for intrapartum intrauterine pressure catheter placement.

Methods: Using a temperature probe, we digitally recorded intrauterine temperature every 10 minutes during labour. Amnioinfusion was administered according to a standard protocol using saline equilibrated to the ambient temperature.

Main outcome measure: Mean intrauterine temperature during labour.

Results: Participants were monitored for a mean of 280 minutes (range 20-820). A total of 164 intrauterine temperature readings in the AI cohort were compared with 797 control measurements. When compared with controls, we observed a lower intrauterine temperature in the AI cohort (36.4 versus 37.4°C, P<0.01). More measurements in the AI cohort were recorded in the presence of intrapartum fever (40% versus 30%). A subgroup analysis of measurements recorded in afebrile parturients revealed an even greater effect of AI (1.5°C decrease, 37.3 versus 35.8°C, P<0.01).

Conclusion: Routine intrapartum AI using saline equilibrated to a mean ambient temperature of 25.0°C reduces intrauterine temperature and may thereby affect fetal core temperature.