Antipyretic Use in Labor May Impact Neonatal Sepsis Calculator Risk Assessment

Background: Use of the neonatal sepsis calculator has become a common strategy for managing late preterm and term infants with sepsis risk factors. This multivariate model includes the following predictors of early onset sepsis (EOS): gestational age, GBS carrier status, duration of rupture of membranes, highest intrapartum temperature (Tmax), and intrapartum antibiotic treatment. The two most important predictors of EOS are Tmax and gestational age. During labor, fever is one of the most important signs of intraamniotic infection. If chorioamnionitis is suspected, broad-spectrum antibiotics may be started to reduce the risk of sepsis in the neonate and the fever may be managed with antipyretics such as acetaminophen. Antipyretics blunt the Tmax, leading to an underestimate of the risk of EOS at birth. If the risk of EOS is underestimated, the clinical recommendation for management will be inappropriate for the infant. We sought to describe antipyretic use in labor and its relationship to maternal Tmax.

Methods: We performed a retrospective chart review of one year of birth data. We generated a report that included all live births of at least 34w0d gestation from 1/1/18 to 12/31/18. 6140 infants were included in the report.

Results: Of 6140 deliveries analyzed, 16.3% (999/6140) of the women in labor received acetaminophen. 50.5% (504/999) of the patients who received acetaminophen had a Tmax of 100.4°F or higher. 49.5% (405/999) of patients who received acetaminophen were afebrile (Tmax < 100.4°F). The mean Tmax of patients who received acetaminophen in L&D was 100.2°F.
Of the patients who were febrile in L&D, 77.7% (504/649) of them received acetaminophen. 52.7% (342/649) of febrile patients received both antipyretics and broad-spectrum antibiotics. 25.0% (162/649) of febrile patients received antipyretics but did not receive broad-spectrum antibiotics. Nearly all (94.5%, 342/362) of the patients who were febrile and treated with broad spectrum antibiotics also received acetaminophen.

Conclusion: We found that antipyretic use in labor is common, even among patients who are afebrile. In these cases, the true Tmax is unknown. Antipyretic use leads to an underestimation of calculated sepsis risk. This impacts the clinical recommendation for antibiotic administration. Also notable is the 25% of febrile patients who received antipyretics but did not receive antibiotics. This may represent the “worst of both worlds”. The calculator underestimates the risk of EOS due to the masking of the true Tmax, and the neonate does not get the benefit of antepartum antibiotics to prevent infection. Varying rates of antipyretic use among obstetric units can lead to the inconsistent performance of the neonatal sepsis calculator. Neonatal care providers and obstetric providers should consider the impact of antipyretics on individual neonatal sepsis risk to avoid missing cases of sepsis.