Even under Canada’s system of universal healthcare, low-income women are less likely than their wealthier counterparts to receive epidural pain relief during childbirth, a new study finds.

The findings mirror those of studies from the U.S. and other countries, and suggest that factors other than health insurance are at work, according to the researchers.

An epidural involves injecting pain medication through a catheter into the lower spine, and is considered the most effective way to relieve pain during childbirth. But studies have suggested that socioeconomics - including income, race or education - sway a woman’s likelihood of having an epidural.

For the new study, reported in the American Journal of Obstetrics & Gynecology, researchers looked at epidural use among more than 200,000 Ontario women who gave birth between 2004 and 2006.

They found that the one-fifth of women from the poorest neighborhoods in the study were 41 percent less likely to have epidural pain relief than the one-fifth of women from the wealthiest neighborhoods. There was a similar discrepancy between the least educated and most educated women.

The effects of income and education were seen even though the researchers accounted for factors like health problems in the mother and pregnancy complications - which can hinder the use of epidurals.

Moreover, given Canada’s universal health system, the findings suggest that factors other than insurance coverage are important, say the researchers, led by Ning Liu of the University of Ottawa.

“We argue that noneconomic maternal characteristics contribute much to the disparity,” Liu’s team writes.

A woman’s education level, for instance, could affect her willingness to have an epidural, the researchers note. Women with more education, they write, may know more about epidurals and be more open to having one.

Race, ethnicity and cultural views may also play a role, according to Liu’s team. There is evidence, for example, that women from Asia often feel that childbirth pain is natural and, therefore, they should “tolerate” it.

In addition, research in the U.S. has found that African Americans are less accepting of epidurals than whites.

Studies have also found that lower-income women are less likely to attend prenatal classes - a place where they would learn about the different types of pain relief available during childbirth.

The findings are based on the childbirth records of 220,814 Ontario women. Of women in the poorest neighborhoods in the province, 56 percent had an epidural, compared with almost 69 percent of women in the wealthiest neighborhoods.

Education appeared to make an even bigger difference. Among the one-fifth of women with the lowest education levels, half had an epidural. That compared with roughly 71 percent of the one-fifth of women with the highest education levels.

Those disparities were least apparent at large, academic medical centers, and most significant at small community hospitals, the researchers found.

Epidurals, in general, were used less often at small hospitals - which is not surprising, according to Liu’s team, since that trend has been documented in other studies. But it is not clear why income- and education-related disparities were greatest at small community hospitals.

They call for more research into the reasons for lower epidural rates among low-income women.

SOURCE: American Journal of Obstetrics & Gynecology, online January 4, 2010.