Intrapartum maternal fever
Although maternal oral temperature is the best indicator of intrauterine temperature, it still underestimates intrauterine temperature by approximately 0.8°C (50). Furthermore, fetal core temperature is another 0.75°C higher than fetal skin and intrauterine temperature (51).
Maternal pyrexia is therefore inevitably associated with elevated fetal temperature and the threshold temperature of 38.0°C, which is widely used as an essential parameter for the definition and diagnosis of intrapartum fever and clinical chorioamnionitis will be associated with fetal brain temperatures of 39.5°C or greater. The impact of this is observed in the risk of encephalopathy to the exposed fetus. For example, the background risk of neonatal encephalopathy of 0.12% among term infants is amplified nearly tenfold to 1.13% with fetal exposure to maternal fever alone (50). In experimental rats, raised brain temperature correlated directly with increased susceptibility to a host of neurotoxic factors (52, 53). In the human newborn, maternal pyrexia was associated with an increased risk of neonatal seizures regardless of whether the pyrexia was of non-infectious origin, for example, epidural analgesia (54). Unsurprisingly, there has recently been a great deal of interest and success with brain cooling for the newborn with significant neonatal encephalopathy.The risk of neonatal encephalopathy with fetal exposure to acidosis alone, defined as a cord pH less than 7.05, is 1.58%. However, the combination of maternal fever and neonatal acidosis results in over a tenfold increase in the risk of neonatal encephalopathy to 12.5%, and this is independent of neonatal sepsis (50). It has been hypothesized that maternal fever increases fetal oxidative stress depleting cellular energy reserves, and increases fetal susceptibility to hypoxic injury. Prophylactic antioxidants have been shown to provide neuroprotection and reduce fetal injury in lipopolysaccharide-based animal models of chorioamnionitis (55-57).
Clinical management
The clinical management of isolated intrapartum maternal fever is based on administration of antipyretics such as paracetamol, tepid sponge, cooling fan, and intrapartum antibiotic prophylaxis in the form of benzylpenicillin every 4 hours until delivery. These antipyretics at least in theory restore the fetomaternal temperature gradient and allow the fetus to rid itself of its metabolic heat. However, there is scant evidence that they improve the prognosis for the baby. In contrast, many clinicians presume that the outlook for the baby improves when the maternal temperature subsides and antibiotics have been administered. There is no antibiotic on the market that crosses the placental barrier in sufficient concentration to eradicate intrauterine infection. Therefore, the bedrock of the management of chorioamnionitis remains delivery of the fetus regardless of its gestational age.
More on the topic Intrapartum maternal fever:
- Medicolegal aspects of intrapartum fetal monitoring
- Arulkumaran S., Ledger W., Denny L., Doumouchtsis S. (eds.). Oxford Textbook of Obstetrics and Gynaecology. Oxford University Press,2020. — 928 p., 2020
- Chapter 9 Abnormal Labor and Intrapartum Fetal Surveillance
- Chapter 24 Infectious Diseases
- Chorioamnionitis
- Intra-amniotic infection, meconium staining of the amniotic fluid, and meconium aspiration syndrome: what is the link?
- Management of preterm prelabour rupture of the membranes
- Infections in Pregnancy
- Chapter 10 Immediate Care of the Newborn
- Chapter 11 Postpartum Care