Women who receive epidurals during labor report less pain than those who choose opiates or natural childbirth, according to a systematic review of evidence.
Yet epidurals bring an increased risk of delivery assisted by forceps or vacuum. The pluses and minuses mean that a woman's decision about pain relief is not clear-cut.
"Each woman will have to weigh how much it means to her to have a spontaneous vaginal delivery versus having more pain in labor," said lead author Dr. Millicent Anim-Somuah of the Liverpool Women's Hospital in England.
On a more positive note, mothers who receive the spinal injections are no more likely than others to require Caesarian sections or to suffer chronic backaches. Their infants are equally healthy soon after birth.
Epidural analgesia involves injecting a local anesthetic into the lower back to block pain impulses from the uterus and birth canal. Obstetricians introduced the technique in 1946, and 58 percent of American women now choose this form of pain relief during childbirth, according to the authors.
The review appears in the most recent issue of The Cochrane Library, a publication of The Cochrane Collaboration, an international organization that evaluates medical research. Systematic reviews draw evidence-based conclusions about medical practice after considering both the content and quality of existing medical trials on a topic.
The reviewers analyzed 21 studies involving more than 6,000 women. Most of the participants were in the United States, England and Australia.
"It's always been suspected that epidurals slow down your labor," said Anim-Somuah. The study confirmed that the nerve block lengthens the stage during which the mother must push the baby through the birth canal. This leads to greater use of medication to stimulate contractions and a 38 percent increase in risk of instrumental delivery.
The precise timing of the epidural injection may be an important factor, says Todd Liu, M.D., a fellow of the American College of Obstetricians and Gynecologists who practices in New Jersey.