Randomized control trial of intravenous acetaminophen for reduction of intrapartum maternal fever

Cooling treatment on the reduction of category II fetal tracings

OBJECTIVES

Epidural-related maternal fever increases the incidence of Category II fetal tracings. To compare the effectiveness of low-flow oxygen inhalation and cooling treatment for parturients with Category II fetal tracings caused by epidural-related maternal fever.

METHODS

We investigated 200 pregnant women who accepted epidural analgesia during labor and had body temperature exceeding 38 °C during labor. Among the patients, 99 and 101 were randomly allocated to receive cooling treatment group (control group) and oxygen inhalation (oxygen group), respectively. The primary outcome was the incidence of Category II fetal heart rate tracings.

RESULTS

The incidence of Category II fetal heart rate tracings in the control group was significantly higher than that in the oxygen group. However, no significant differences were noted between the two groups in terms of the Apgar scores; amniotic fluid turbidity; or maternal outcomes, including cesarean section rate, forceps delivery rate, lateral resection rate, manual removal of placenta rate, the amount of intrapartum hemorrhage, and hemorrhage at postpartum 2 h. Oxygen inhalation therapy was more effective than cooling treatment in reducing the incidence of Category II tracings.

CONCLUSION

Low-flow and short-term oxygen inhalation for parturients with epidural-related maternal fever reduces the incidence of Category II fetal heart rate tracings, but had no significant influence on the mode of delivery or neonatal outcomes.

Maternal fever in labor: etiologies, consequences, and clinical management

Intrapartum fever is common and presents diagnostic and treatment dilemmas for the clinician. True maternal sepsis is rare; only an estimated 1.4% of women with clinical chorioamnionitis at term develop severe sepsis. However, the combination of inflammation and hyperthermia adversely impacts uterine contractility and, in turn, increases the risk for cesarean delivery and postpartum hemorrhage by 2- to 3-fold. For the neonate, the rates of encephalopathy or the need for therapeutic hypothermia have been reported to be higher with a maternal fever >39°C when compared with a temperature of 38°C to 39°C (1.1 vs 4.4%; P<.01). In a large cohort study, the combination of intrapartum fever and fetal acidosis was particularly detrimental. This suggests that intrapartum fever may lower the threshold for fetal hypoxic brain injury. Because fetal hypoxia is often difficult to predict or prevent, every effort should be made to reduce the risk for intrapartum fever. The duration of exposure to epidural analgesia and the length of labor in unmedicated women remain significant risk factors for intrapartum fever. Therefore, paying careful attention to maintaining labor progress can potentially reduce the rates of intrapartum fever and the risk for cesarean delivery if fever does occur. A recent, double-blind randomized trial of nulliparas at >36 weeks' gestation demonstrated that a high-dose oxytocin regimen (6×6 mU/min) when compared with a low-dose oxytocin regimen (2×2 mU/min) led to clinically meaningful reductions in the rate of intrapartum fever (10.4% vs 15.6%; risk rate, 0.67; 95% confidence interval, 0.48-0.92). When fever does occur, antibiotic treatment should be initiated promptly; acetaminophen may not be effective in reducing the maternal temperature. There is no evidence that reducing the duration of fetal exposure to intrapartum fever prevents known adverse neonatal outcomes. Therefore, intrapartum fever is not an indication for cesarean delivery to interrupt labor with the purpose of improving neonatal outcome. Finally, clinicians should be ready for the increased risk for postpartum hemorrhage and have uterotonic agents on hand at delivery to prevent delays in treatment.

Fetal and maternal inflammatory response in the setting of maternal intrapartum fever with and without clinical and histologic chorioamnionitis

BACKGROUND

Both infectious and noninfectious causes of maternal fever have been linked to adverse neonatal outcomes including low Apg0ar scores, respiratory distress, hypotonia, and neonatal seizures. Even in the absence of infection, the occurrence of intrapartum fever is a strong risk factor for poor long-term neonatal developmental outcomes, including encephalopathy, cerebral palsy, and neonatal death.

OBJECTIVE

The primary objective of this study was to compare intrapartum and postpartum maternal and fetal umbilical cord serum levels of cytokines RANTES, interferon-ɣ, interleukin-1β, interleukin-2, interleukin-4, interleukin-6, interleukin-8, interleukin-10, interleukin-13, and tumor necrosis factor-α among nonfebrile patients, febrile patients without clinical chorioamnionitis, and febrile patient with clinical chorioamnionitis.

STUDY DESIGN

This study was conducted at the Richmond University Medical Center from May 15, 2020 to July 16, 2019. During this time, we recruited 30 nonfebrile patients at >36 gestational weeks who were in labor and collected umbilical cord and pre- and postdelivery maternal serum samples to evaluate the cytokine levels. Placentas were collected for pathologic review and to evaluate the histopathologic findings. These results were compared with 121 patients who developed a fever of >38°C during labor. The febrile patients were further divided based on the presence or absence of clinical chorioamnionitis. A secondary analysis was performed based on the presence of absence of histologic chorioamnionitis. Statistical analysis was performed using IBM Statistical Package for the Social Sciences version 25.0. For the 3 group comparisons, a P value of <.017 was considered statistically significant after application of a Bonferroni correction.

RESULTS

A total of 151 patients were included in the study; 30 were nonfebrile patients, 46 were febrile patients with a diagnosis of clinical chorioamnionitis, and 75 were febrile patients without clinical chorioamnionitis. Compared with nonfebrile patients, umbilical cord serum interferon-ɣ, interleukin-1β, interleukin-6, interleukin-8, RANTES, and tumor necrosis factor-α levels were elevated in the presence of maternal hyperthermia irrespective of the diagnosis of clinical chorioamnionitis. Interleukin-6 umbilical cord levels were more than doubled from 63.60 pg/mL (6.09-1769.03 pg/mL) in febrile patients with no clinical chorioamnionitis to 135.77 pg/mL (1.86-6004.78 pg/mL) in febrile patients with clinical chorioamnionitis, making it the only cytokine that was significantly different between these 2 groups. When comparing the intrapartum maternal serum, we found a significant elevation in the interleukin-10, RANTES, and tumor necrosis factor-α levels in the febrile group irrespective of the presence of clinical chorioamnionitis when compared with the nonfebrile group. In the postpartum maternal blood evaluations, tumor necrosis factor-α was the only cytokine that was significantly higher in febrile patients than in nonfebrile controls.

CONCLUSION

In the setting of intrapartum fever, maternal cytokine profiles were similar irrespective of the diagnosis of clinical chorioamnionitis. Even in the absence of clinical or histologic chorioamnionitis, maternal hyperthermia induced elevations in fetal cytokines.

Mechanistic Coupling of a Novel in silico Cotyledon Perfusion Model and a Physiologically Based Pharmacokinetic Model to Predict Fetal Acetaminophen Pharmacokinetics at Delivery

Little is known about placental drug transfer and fetal pharmacokinetics despite increasing drug use in pregnant women. While physiologically based pharmacokinetic (PBPK) models can help in some cases to shed light on this knowledge gap, adequate parameterization of placental drug transfer remains challenging. A novel in silico model with seven compartments representing the ex vivo cotyledon perfusion assay was developed and used to describe placental transfer and fetal pharmacokinetics of acetaminophen. Unknown parameters were optimized using observed data. Thereafter, values of relevant model parameters were copied to a maternal-fetal PBPK model and acetaminophen pharmacokinetics were predicted at delivery after oral administration of 1,000 mg. Predictions in the umbilical vein were evaluated with data from two clinical studies. Simulations from the in silico cotyledon perfusion model indicated that acetaminophen accumulates in the trophoblasts; simulated steady state concentrations in the trophoblasts were 4.31-fold higher than those in the perfusate. The whole-body PBPK model predicted umbilical vein concentrations with a mean prediction error of 24.7%. Of the 62 concentration values reported in the clinical studies, 50 values (81%) were predicted within a 2-fold error range. In conclusion, this study presents a novel in silico cotyledon perfusion model that is structurally congruent with the placenta implemented in our maternal-fetal PBPK model. This allows transferring parameters from the former model into our PBPK model for mechanistically exploring whole-body pharmacokinetics and concentration-effect relationships in the placental tissue. Further studies should investigate acetaminophen accumulation and metabolism in the placenta as the former might potentially affect placental prostaglandin synthesis and subsequent fetal exposure.