Fever in labour and neonatal encephalopathy: a prospective cohort study

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Abstract

Objective To determine whether the reported association of maternal fever with neonatal encephalopathy is independent of other associated intrapartum risk factors.

Design Prospective cohort study.

Setting Dublin teaching hospital delivery ward.

Population 4915 low risk women in labour at 36-41 weeks of gestation.

Methods Using logistic regression with odds ratios and 95% confidence intervals, the incidence of neonatal encephalopathy and other neonatal outcomes of women who had an intrapartum fever >37.5° C was compared with those who did not.

Results The cohort comprised 33% of all deliveries during the study period. Neonatal encephalopathy was diagnosed in 3.25/1000 births. The incidence of intrapartum fever was 6.8%. Maternal fever was strongly associated with neonatal encephalopathy (crude OR 10.8, 95% CI 4.0-29.3). Univariate analysis showed maternal fever was associated with epidural analgesia, nulliparity, induction, longer labour, oxytocin administration, greater fetal birthweight and gestational age and instrumental vaginal delivery, but not with prolonged (>24hours) prelabour rupture of the membranes. The association of fever with neonatal encephalopathy persisted having adjusting for these covariates (adjusted OR 4.72, 95% CI 1.28-17.4).

Conclusions The relationship between maternal intrapartum fever and neonatal encephalopathy is independent of other known intrapartum risk factors. This provides further evidence for the role of inflammatory processes in the aetiology of neonatal neurological morbidity.

Introduction

There is increasing evidence that both infection and maternal fever in labour are important factors associated with the subsequent development of cerebral palsy in both preterm1 and term infants2. An association between maternal fever and neonatal encephalopathy has also been suggested3, using case-control methodology. It is not clear, however, whether fever is simply a marker for other intrapartum risk factors.

The aim of this study was to investigate the association between fever and neonatal encephalopathy using a large cohort of prospectively collected labours. By controlling for intrapartum factors we aimed to discover whether fever is a risk factor for neonatal encephalopathy independent of other intrapartum risk factors, and examine possible causes for an association.

Section snippets

Methods

The cohort of women for this study was derived from those recruited to a randomised controlled trial in the National Maternity Hospital, Dublin to assess the effect of the routine use of an admission cardiotocograph on neonatal outcome. In this unit labour in nulliparous women is actively managed4; multiparous women also undergo routine early amniotomy. Women were recruited immediately after amniotomy and randomised either to a 20-minute admission cardiotocograph or no cardiotocograph. Women

Results

A total of 4915 women were included in the analysis. Of these, 336 (6.8%) developed an intrapartum fever >37.5°C. Sixteen new born infants developed encephalopathy (3.26 per 1000), seven (43.8%) whose mother's labour was complicated by maternal fever. There were two early neonatal deaths (0.4 per 1000), both in babies with multiple congenital anomalies.

Univariate analysis showed that the development of a maternal fever was associated with nulliparity, induced labour, the use of epidural

Discussion

These data show that maternal fever in labour is strongly associated with neonatal encephalopathy. As a crude risk factor, it is even more predictive than an abnormal intrapartum cardiotocograph6. In the United States collaborative perinatal project, more than half of such babies died or developed disability7. The complexity of the relationship between the intrapartum variables, fever and adverse neonatal outcome has deterred some authors3., 8., 9. from controlling for intrapartum factors such

Conclusion

This analysis shows that maternal fever in labour is strongly and independently associated with early neonatal morbidity, most significantly in the incidence of neonatal encephalopathy. Maternal fever is a better indicator of a fetus at risk of encephalopathy than is an abnormal cardiotocograph, although even if a causal relationship were proven, alterations in management may not change the neonatal outcome. Most importantly, the establishment of an intrapartum fever as an independent risk

Acknowledgements

The authors would like to thank the women who participated in this study, the midwives of the delivery ward in The National Maternity Hospital, and Professor C. Redman, Professor P. Steer, Dr J. Murphy and Dr P. Brocklehurst for discussion and advice in the preparation of this manuscript. This project was funded by the National Maternity Hospital Research Fund of the National Maternity Hospital, Holles St, Dublin 2, Ireland.

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