Elevated Temperature With Epidural Analgesia Linked to Neonatal Harm
"January 30, 2012 — Maternal fever that accompanies epidural analgesia is associated with neurological depression in the neonates, according to a study published online January 30 in Pediatrics.
More than 90% of fever during labor is related to epidural analgesia, and not infection. Studies have associated intrapartum maternal fever with neonatal adverse neurological events, including hypotonia, lower Apgar scores, increased incidence of seizures and stroke, elevated need for cardiopulmonary resuscitation or assisted ventilation, and motor problems or cerebral palsy in early childhood. To distinguish the putative roles of fever vs epidural analgesia in contributing to or causing these problems, Elizabeth A. Greenwell, ScD, from the Harvard School of Public Health, Boston, Massachusetts, and colleagues conducted a retrospective cohort investigation of all infants born at Brigham and Women's Hospital in Boston in 2000.
The study evaluated low-risk, nulliparous, singleton deliveries, excluding women with medical conditions, elevated temperature on admission, and newborns with infections of other conditions that might be associated with adverse outcomes but independent of maternal fever. Of the 3209 pairs evaluated, 2784 of the mothers received epidurals, and 425 did not.
The investigation considered the possible association of epidural analgesia to adverse neonatal outcomes and the association of neonatal outcomes with 4 levels of temperature elevation among women receiving epidurals. The study did not include women with fever who did not have an epidural because there were too few of them for statistical significance.
Temperature exceeding 99.5°F developed in 1246 (44.8%) of the 2784 women receiving epidurals, and in 62 (14.6%) of those women not receiving the analgesic. The researchers considered this level "temperature elevation." They defined "maternal fever" as temperature above 100.4°F. Of women receiving epidurals, 535 (19.2%) developed fevers compared with 10 of 425 (2.4%) of those not receiving epidurals.
For women with normal temperatures, the percentage of infants with an adverse outcome was similar, whether the women did or did not receive epidurals. Among women receiving epidurals, however, the proportion of infants experiencing adverse outcomes was directly proportional to the magnitude of temperature elevation. For example, the proportion of infants with hypotonia increased from 10.8% among women with maximum temperatures of 99.5°F to 25.2% among women with a maximum temperature above 101°F. Similarly, the proportion of infants requiring resuscitation approximately tripled, from 4.4% to 12.2%, with rise in temperature.
The researchers conclude that "increased maternal temperature, regardless of etiology, may have implications for the fetus." After adjusting for confounding factors, they associated maternal fever above 101°F with a "two- to sixfold increase in the occurrence of all adverse neonatal outcomes examined," they write.
"In contrast," they continue, "we found no increase in adverse neonatal outcomes between women receiving and not receiving epidural in the absence of maternal temperature elevation, suggesting that epidural analgesia without accompanying maternal fever does not have an immediate effect on neonatal status."
Limitations of the study include insufficient numbers of febrile women not receiving epidurals, as well as masking some infant infections with maternal antibiotics.
Although exactly how epidurals cause fever and how fever causes adverse neonatal outcomes remain unknown, inflammation may play a role, the researchers write."