Race and ethnicity may not play role in restless leg syndrome during pregnancy

UNIVERSITY PARK, Pa. — While a person’s risk for restless leg syndrome (RLS) increases during pregnancy, the exact reason for this is unknown. A new study suggests that at least one factor – a person’s race or ethnicity – may not play a role.

A team of researchers, led by Xiang Gao, professor of nutritional sciences, and Muzi Na, assistant professor of nutritional sciences, examined whether race, ethnicity, and other factors, including nutritional status, play a role in RLS during pregnancy in a new study published in Neurology, the medical journal of the American Academy of Neurology. Though they found differences between different racial and ethnic groups, they do not believe that race was the cause of the differences.

“Restless legs syndrome occurs more often in pregnant women than in the general population, and it can be associated with some pregnancy complications and adverse birth outcomes,” said Gao. “The percentage of pregnant women with restless legs syndrome varies greatly by region and country, but few studies have looked at the risk of restless legs syndrome by race or ethnicity in a multi-racial cohort.”

The study involved 2,704 healthy women recruited from the Eunice Kennedy Shriver National Institute of Child Health and Human Development Fetal Growth Studies. The women were between eight and 13 weeks’ pregnant without prior restless legs syndrome or other major health problems prior to pregnancy. Participants included 709 White women, 765 Black women, 774 Hispanic women, and 456 Asian/Pacific Islander women.

At the beginning of the study, participants completed a questionnaire on social demographic, clinical, and reproductive factors including those that could affect their risk of developing RLS, such as age, body weight, race/ethnicity, and number of prior pregnancies. Participants were asked about any current RLS at the beginning of the study and then again five times throughout their pregnancy.

RLS symptoms included the urge to move the legs accompanied by unpleasant sensations; urge to move or unpleasant sensation relieved by movements; symptoms that appear worse at rest and are partially relieved by activity; symptoms that are worse in the evening and during the night.

Of the participants, 490 women — or 18% — experienced restless legs syndrome symptoms during their pregnancy. The breakdown by race/ethnicity was 20% for white women, 15% for Black women, 17% for Hispanic women, and 21% for Asian women.

“While we found that the incidence of restless legs syndrome in pregnancy was much higher than in the general population and did, indeed, differ by race and ethnicity,” Gao said. “When researchers adjusted for variables such as age, nutritional factors, and number of pregnancies, however, we saw little difference in risk of restless legs syndrome in pregnancy between the different groups. The data suggest that the disparity is likely not related to race and ethnicity.”

A limitation of the study was that participants were overall healthier than the general population, having entered the study with no major chronic diseases, so the results may not apply to everyone.

Jing Wu, Glotech Inc.; and Mengying Li, Stefanie N. Hinkle and Cuilin Zhang, National Institute of Child Health and Human Development, also participated in this work.

The study was supported by the Division of Intramural Population Health Research, Eunice Kennedy Shriver National Institute of Child Health and Human Development of the National Institutes of Health.