WASHINGTON (AP) -- Dr. Mark Rosen offers San Francisco women an option to relieve childbirth pain not found in most U.S. hospitals: laughing gas.

It's not nearly as good as an epidural, he admits - you'll still feel a lot of pain. But for women who go without an epidural, Rosen calls it a harmless way to "take the edge off."

Well over 2 million American women a year get an epidural, the undisputed king of pain relief, albeit one with some lingering controversy. But small hospitals are far less likely to offer epidurals and more advanced "walking epidurals" are offered to only a fraction of women, according to surprising new research on childbirth.

The report is prompting calls for more attention to alternatives, from Rosen's nitrous oxide to laboring in warm water, that might help women who can't get or don't want an epidural.

Pain experts say pregnant women should have candid talks with their obstetrician and hospital anesthesia staff to ensure they've picked a spot to give birth that offers the pain relief they want.

"The most important thing is the information be accurate," stresses Dr. William Camann of Brigham & Women's Hospital, vice president of the Society for Obstetric Anesthesia and Perinatology.

Camann notes that pain medications have changed greatly and cautions women against making decisions based on outdated concerns.

For instance, women need not choose between natural-childbirth techniques and medication because they're actually complementary, he says. Camann coined the term "epi-doula" for the increasing practice of using a doula, a layman trained in labor support, during early labor and an epidural for the more severe pain that comes later.

Maureen Corry of New York's Maternity Center Association also urges women to think ahead and avoid arriving at the hospital in labor only to learn it can't follow a chosen pain plan. Her association spurred the analysis published in last week's American Journal of Obstetrics and Gynecology.

More than 150 years after anesthesia was introduced to childbirth, the issues of access to and effectiveness of pain-relief methods remain remarkably emotionally charged, says the new analysis of labor pain.

Pregnant women may find valuable information in the findings, which include:

-More than half of laboring women get an epidural, although far fewer do at small or rural hospitals that often don't have round-the-clock anesthesiologists.

-With epidurals, medication seeps through a tube into space surrounding the spinal cord to block pain from the abdomen down. Today's dosages take effect in 20 minutes, leave women able to sit up and push, and don't drug babies.

-Epidurals don't seem to increase Caesarean sections, but can lengthen labor roughly half an hour, although some studies suggest it's longer. They also may raise a mother's temperature, prompting some hospitals to test the newborn for infection, and increase use of forceps. But proving such risks is hard, in part because women with longer, more difficult labors are more prone to use painkillers.

-Walking epidurals, officially called "combined spinal/epidurals," offer advantages. A lower-dose painkiller is injected into a different spot near the spinal cord, causing immediate pain relief. When that injection wears off in two hours, the regular epidural kicks in. Most women physically can walk, although some hospitals keep them in bed. While popularity is jumping, the latest data suggests few mothers get them.

Many "hospitals can't afford to have the luxury of these highly specially trained anesthesiologists," laments New York University obstetrics chair Dr. Charles Lockwood, also with the American College of Obstetrics and Gynecology. "It's a real dilemma."

-Nitrous oxide is offered by the University of California, San Francisco's Rosen and in Britain. Inhaling harmless low doses with each contraction provides only mild relief. But Rosen says it's likely better than the narcotic painkillers up to half of women receive and notes that narcotics can reach a baby's bloodstream.

Non-drug methods like Lamaze breathing techniques have long been popular. But the report advocates wider use of additional non-drug options: Soaking in warm water, the help of a doula, and staying upright or squatting during labor.

Depending on how long they're needed, doulas can cost dlrs 300 to dlrs 1,500, an expense not covered by insurance. And though few delivery rooms are considering laughing gas, many are adding bathtubs for a good soak.

Copyright 2002 The Associated Press. All rights reserved.