New Analysis Shows Racial and Ethnic Differences in the Relationship Between Pregnancy and High-Impact Pain

Non-Hispanic White women in the United States are less likely to have high-impact pain when they’re pregnant than at other times in their lives, but this pattern is not seen in non-Hispanic Black or Hispanic White women, according to a new analysis of national survey data. The analysis, published in the Journal of Women’s Health, was performed by researchers from the National Institutes of Health’s Office of Research on Women’s Health and National Center for Complementary and Integrative Health.

Previous studies both in animals and in human populations have provided evidence that pregnancy is associated with a reduction in sensitivity to pain. The purpose of this study was to compare high-impact pain at the population level in currently pregnant women, those who had never been pregnant, and those who had previously been pregnant, and to assess the combined impact of Hispanic ethnicity and race. Data for women aged 18 to 44 from the years 2012 through 2015 of the National Health Interview Survey, a nationally representative annual survey of the noninstitutionalized civilian U.S. population, were used. 

Participants’ responses to two survey questions—one about how often they have pain and one about the severity of pain—were combined to create five categories of pain severity using a previously validated coding scheme. Women in the two highest pain categories were classified as having high-impact pain. Data are reported for only three racial/ethnic groups (non-Hispanic White, non-Hispanic Black, and Hispanic White) because sample sizes in the other groups were small. 

The data showed the following:

• Among the entire group of participants (all racial/ethnic groups considered together), women who had previously been pregnant were more likely to report high-impact pain than those who had never been pregnant and those who were currently pregnant.
• Among non-Hispanic White women, those who had previously been pregnant were more likely to report high-impact pain than those who were currently pregnant but not those who had never been pregnant. No differences in high-impact pain prevalence among the three pregnancy status groups were seen in non-Hispanic Black women or Hispanic White women.
• Among women who had never been pregnant, Hispanic White women had less high-impact pain than non-Hispanic White and non-Hispanic Black women.
• An additional analysis, for which data were only available for 2012 and for women who had never been pregnant, showed that women who had menstrual problems were more likely to have high-impact pain. The proportion of women with menstrual problems was similar in the three racial/ethnic groups, and there was no interaction between menstrual problems and race/ethnicity in their impact on whether women reported high-impact pain.

These results indicate that the relationship between pregnancy status and pain differs among racial/ethnic groups and that these differences are not attributable to differences in menstrual pain. Pregnancy has been described as a stress test, a time of substantial biological and psychological changes. These changes may not provide the same protection against pain for non-Hispanic Black and Hispanic White women as they do for non-Hispanic White women. In addition, pregnancy-induced drivers of pain may be more prominent in non-Hispanic Black and Hispanic White women than in non-Hispanic White women. The investigators who conducted this analysis suggested that future research to identify the factors responsible for race and ethnicity differences in high-impact pain across pregnancy status will help improve the understanding and treatment of pain for all women.