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ABSTRACT & COMMENTARY
In order to determine the effect of the increase in maternal temperature known to be associated with epidural analgesia, Lieberman et al studied 1657 nulliparous women with term pregnancies and singleton vertex fetuses who were afebrile when admitted for delivery. This study focused not only on the number of women who developed an intrapartum fever (a temperature greater than 100.4ºF) but also on how many of their infants were evaluated for sepsis and received antibiotic treatment.
Overall, 63% of the women in the trial received epidural anesthesia. These patients were more likely to have had induced labors and were less likely to have had active management of labor. Fever occurred in 14.5% of women who received epidural anesthesia (n = 152) as compared to only 1% of those who did not (n = 6). While few women without an epidural became febrile during labor, the rate increased as labor progressed in women who had received an epidural, reaching 36% for women with labors greater than 18 hours.
Work-ups for neonatal sepsis, which included a blood culture and complete blood count, were performed in 25.1% of all infants, 34% (n = 356) in the epidural group and 9.8% (n = 60) in the group without epidurals. Antibiotic treatment, usually with ampicillin and gentamicin, was four times more likely in neonates whose mothers had received an epidural, 15.4% vs. 3.8%. Of the 416 infants evaluated for infection, only four had documented sepsis, three whose mothers had epidurals. The investigators examined why 25% of infants were evaluated for sepsis when only 9.5% of mothers developed a fever during labor. In fact, maternal fever accounted for only one-third of neonatal evaluations for sepsis. Even after adjusting for birth weight, gestational age, induction of labor, premature rupture of the membranes, and treatment with an active management of labor protocol, the infants of women who had received an epidural remained three times more likely to be evaluated for sepsis even in the absence of fever. Analysis revealed that longer lengths of labor and, in particular, ruptured membranes of greater than 18 hours were responsible for the higher rate of sepsis evaluation.
The authors conclude that the use of epidural analgesia during labor significantly increases the likelihood that the neonates will be evaluated for sepsis and receive antibiotic therapy.
Epidural analgesia is known to increase maternal temperature during labor, possibly by altering thermoregulation. In the present study, 14.5% of women who received an epidural had a temperature increase greater than 100.4ºF, a level that usually leads to an evaluation for chorioamnionitis and maternal antibiotic therapy. How often laboring patients were treated with antibiotics is not described in this paper. Rather, the study examined how frequently neonates whose mothers had epidural analgesia were evaluated for sepsis and received antibiotics. Overall, 460 infants (25%) had such a work-up. More than half of these evaluations were performed in patients who had an epidural but were not febrile. Why? The risk factors used to determine whether a sepsis evaluation would be performed included ruptured membranes for greater than 12 hours (more than 40% of patients who received epidural analgesia had labors lasting more than 12 hours), a maternal white blood cell count greater than 15,000/mm3 (not unusual in laboring women), and neonatal symptoms in the delivery room, including poor color or tone. One out of four of the term infants delivered in this study had a workup for sepsis, but less than one in 100 of those evaluated were actually found to be septic. The problem in this study appears not to be with epidural analgesia but with the criteria used for the evaluation of neonatal sepsis.