Effects on fetal and maternal temperatures of paracetamol administration during labour: a case-control study.

OBJECTIVE To study the effect of paracetamol (acetaminophen) on maternal and fetal temperatures in labour. STUDY DESIGN From a cohort of 185 women with continuous maternal axillary and fetal scalp temperature recordings in labour, 18 women treated with 1000mg paracetamol orally for pyrexia and 36 untreated controls matched for parity, cervical dilatation, and epidural analgesia were selected. Electronically stored temperature data were analysed offline post hoc. The dual temperatures recorded every 30min from 60min before (T-60) paracetamol administration (T0) until delivery, were noted. Longitudinal data were compared with Wilcoxon matched-pairs signed-ranks test and cross-sectional data with Mann-Whitney U test. Shapes of the temperature curves were compared with mixed-effect models statistics for repeated measurements. The main outcome measures were temperature changes after paracetamol. A two-tailed P<0.05 was considered significant. RESULTS Prior to T0 maternal and fetal temperatures increased in the paracetamol group, but after T0 no significant changes (P≥0.1) were seen when compared with Wilcoxon signed-ranks test. In the control group, both temperatures increased from T-60 and onwards. Delta-temperatures (fetal minus maternal temperature) remained unchanged in both groups. Analyses of the mixed-effect models showed a significant difference (P=0.01) in the shape of fetal temperature curves between the paracetamol and control groups, but no significant difference (P=0.4) in maternal temperature curve shapes. CONCLUSION In febrile parturients, neither maternal nor fetal temperatures dropped after paracetamol, but paracetamol halted an increasing trend and stabilised the fetal temperature. The effect of paracetamol on maternal temperature was inconclusive.