Incidence of fever in labor and risk of neonatal sepsis

Abstract

Background: The current recommendation regarding the management of a term newborn delivered of a mother with an intrapartum fever or a diagnosis of clinical chorioamnionitis is that the neonate should have baseline laboratory work drawn along with blood cultures and be universally treated with antibiotics until culture results return. These guidelines report that the rate of intrapartum fever is about 3%; however, a few large studies suggest that the rate is higher at about 7%.

Objective: We sought to prospectively evaluate the rate of fever during labor in a large number of deliveries and determine the rate of early-onset neonatal sepsis in newborns delivered from mothers with an intrapartum fever compared with newborns delivered from mothers without intrapartum fever.

Study design: This was a prospective cohort study of all temperatures obtained in women in labor from Jan. 1, 2011, through June 30, 2014. Every patient with a fever of ≥38°C at ≥36 weeks' gestation was evaluated for gestational age, parity, spontaneous or induced labor, group B streptococcus status, regional anesthesia, mode of delivery, treatment with intrapartum antibiotics, and whether a clinical diagnosis of chorioamnionitis was made by the managing physician. Neonates were assessed for blood culture results, neonatal intensive care unit admission, length of stay, and any major newborn complications. Statistical analysis involved χ², Fisher exact, and Student t test.

Results: A total of 412 patients (6.8%; 95% confidence interval, 6.2-7.5%) developed a fever in 6057 deliveries at ≥36 weeks' gestation. No cases of maternal sepsis occurred. Of the 417 newborns (5 sets of twins), only 1 (0.24%; 95% confidence interval, 0.01-1.3%) developed early-onset neonatal sepsis with a positive blood culture for Escherichia coli. There were 4 cases (0.07%; 95% confidence interval, 0.02-0.18%) of early-onset neonatal sepsis in the 5697 newborns (52 sets of twins) delivered from mothers who were not febrile and this difference was not significant (P = .3). The positive blood cultures in these 4 neonates were 3 group B streptococcus and 1 Enterococcus. The overall rate of early-onset neonatal sepsis in this population of newborns delivered at ≥36 weeks' gestation was 0.82/1000 deliveries.

Conclusion: The incidence of an intrapartum fever of ≥38°C in pregnancies at ≥36 weeks' gestation is common at 6.8% and this is consistent with the findings of a few other large retrospective studies. The rate of an intrapartum fever occurs in approximately 1 in 15 women in labor. The risk of neonatal sepsis in newborns delivered of mothers with intrapartum fever or a diagnosis of clinical chorioamnionitis is low at 0.24%, a rate that is <1 in 400. The recommendation for universal laboratory work, cultures, and antibiotic treatment pending culture results for this newborn population needs further examination.

Keywords: clinical chorioamnionitis; group B streptococcus; inflammation; intraamniotic infection; intrapartum antibiotics; microbial infections in pregnancy; neonatal intensive care unit admission; newborn blood cultures; sepsis.