(Reuters Health) - Access to pain relief during childbirth in the U.S. may vary depending on where women live, a study suggests.

Researchers who analyzed more than 2.6 million deliveries in 2015 found the proportion of women receiving epidurals or spinal blocks to manage pain during labor ranged from a low of 25 percent in Maine to a high of 79 percent in Nevada,

Very little of this difference - just 5.4 percent - could be explained by differences between states in health market factors like the size of the anesthesiologist workforce, the study found.

“Unmeasured patient-level and hospital-level factors may account for the degree of variation,” said Dr. Alexander Butwick of Stanford University School of Medicine in Palo Alto, California.

“This speaks to the fact that mothers should ask lots of questions about the extent of services provided at their delivery hospital, which includes: obstetric, neonatal, as well those related to anesthesia, and the types of pain relief offered,” Butwick said by email.

It isn’t enough for women to ask if their hospital provides epidurals, Butwick added. Women should also ask whether it’s available 24/7 and whether clinicians who provide anesthesia are working “in-house” or providing on-call coverage from home.

Women who receive epidurals or spinal blocks for pain relief during labor tend to have less discomfort and be less likely to require additional pain relief than women who receive opioids to manage labor pain, researchers note in JAMA Network Open.

For a spinal block, the anesthetic is injected once. For an epidural, the anesthetic is administered continuously through a catheter placed in the spinal canal.

Doctors recommend that all women have access to anesthesia during labor, and that hospitals with dedicated labor and delivery services make this option available.

Anesthesia during labor was less common in states with large rural populations like Arkansas, Vermont and Mississippi, the study found.

“Some of these rural states may have more limited availability of anesthesia staff at the hospitals where these women deliver,” Butwick said. “More research is needed to confirm this, and we also cannot rule out the possibility that differences may exist across states in patients’ preferences for pain relief in labor.”

The type of anesthesia delivered in epidurals may make it easier for women to have vaginal deliveries and to be awake during delivery if they need to have a cesarean section than other techniques like nitrous oxide or intravenous opioids, Butwick said.

Risks associated with epidurals include headaches as well as more rare but serious complications like infections, bleeding around the spinal cord and permanent nerve damage.

The study wasn’t a controlled experiment designed to determine whether or how the type of pain relief or the absence of pain relief during labor might directly impact health outcomes for mothers or babies.

Whether to use pain relief during vaginal deliveries is also very much about mothers’ personal preferences and beliefs, and women who receive epidurals or spinal blocks don’t necessarily receive better care than mothers who don’t, said Dr. Philip Hess, a professor at Harvard Medical School and director of obstetric anesthesia at Beth Israel Deaconess Medical Center in Boston.

“The choice of type and amount of pain relief should be made by a mother in labor based on what she is experiencing - no two women feel the same amount and type of pain,” Hess, who wasn’t involved in the study, said by email. “If the pain of labor is not distracting her from experiencing a satisfying birth then no medication may be warranted.”

SOURCE: bit.ly/2RI2G8d JAMA Network Open, online December 28, 2018.