May 1997
BOSTON
— A new study has found that babies born to women given epidurals during
labor were more likely to receive lumbar punctures than babies born to women who
were not given the anesthetic.
The study analyzed records from 1990 to 1994 of 1,657 women who had gone to
Brigham and Women's Hospital to have their first babies. The researchers
compared women who were administered bupivacaine and fentanyl with those who
were given other types of pain relief or who received no pain medication at all.
The study was published in Pediatrics.
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The study found that about 14% of women given bupivacaine and fentanyl developed a fever of at least 100.4º F during labor and another 38% were in labor for more than 12 hours after their membranes ruptured. Thirty-four percent of their babies received lumbar punctures, and of that number, about 15% of the babies were treated for sepsis.
By sharp contrast, however, only 1% of the other group who opted for different or no medication suffered a fever and only 8% had a long labor. But only about 10% of their babies were tested for sepsis and of those, only 4% were treated.
Overall, 63% of the women (1,047) studied received epidurals, but their number accounted for 96% of those who developed fevers during labor. Their babies accounted for around 86% of all newborns tested for sepsis and about 87% of those given some form of antibiotics.
However, one thing the study could not positively conclude was that epidurals either caused infections or increased the risk of actual infections in the newborns, the authors stressed.
Also, the study did not review whether the newer kinds of "walking'' epidurals would show the same effects as the ones in the study. These epidurals use a different mix of drugs in lower doses than the standard epidurals, the authors said.
The study's researchers said doctors must find a better way to identify which newborns need a lumbar puncture. A baby is not in danger unless the mother has an infection, but it is difficult to identify which women have infections because many telltale signs like elevated white blood cell counts and abdominal tenderness are normal characteristics of women in intrapartum.
Epidurals account for almost 32% of medications given to intrapartum patients. For more than 1 million women a year, epidurals are the drugs of choice because they allow women to be awake and push during intrapartum and are less likely than some other drugs to reach the fetus.
Previous studies have documented an increase in intrapartum temperature associated with the use of epidurals.
Estimates in the rate of rise of maternal temperature from epidurals range from 0.08°/hr. to 0.14°/hr. It has also been suggested through these studies that fetal harm may result from maternal temperature elevation during labor. One study measuring fetal skin temperature during labor found that in 9% of the cases reviewed where the mother was given an epidural, fetal skin temperature reached 39° C, as compare with the non-epidural group in which no fetuses had as high a skin temperature. They suggest that as fetal core temperature is likely to be 0.75° C higher than fetal skin temperature, core temperature may sometimes reach 40° C, a temperature that in adults is associated with heatstroke risk.
Ellice Lieberman, MD, the study's lead author and director of obstetric and perinatal epidemiology at Brigham and Women's, said she does not want to stress-out young mothers-to-be with her findings, but feels all women should have this information when deciding on an epidural.
"The testing process [to see if the newborns have sepsis] is extremely painful because it involves drawing vials of blood and sometimes doing a lumbar puncture to remove fluid from the infant's spine,'' she said. "It can become an ordeal for the infant.''
Lieberman also said the research findings can be of great benefit to pediatricians who will be able to better distinguish and evaluate which infants are actually infected with sepsis.
Another of the report's authors, Steven Ringer, MD, director of newborn services at Brigham and Women's, has begun a new study to identify which babies can safely do without a sepsis work-up following their birth.
"New mothers keep looking for a magic bullet that says this is an infected baby and this is not an infected baby, but we have not found one yet,'' he said.
For more information:
- Lieberman E, et. al. Epidural, maternal fever, and neonatal sepsis evaluation. Pediatrics. 1997;99:415-420.
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