A study indicates that estrogen plays an important role in triggering restless legs syndrome (RLS) during pregnancy, researchers from Germany report in the journal Sleep.

“We, for the first time, have quite direct evidence that RLS in pregnancy ... is obviously directly related to hormonal changes (estrogens),” Dr. Thomas Pollmächer, principal investigator on the study, noted in an email to Reuters Health.

In the study, ten pregnant women with RLS and nine pregnant healthy “controls” provided blood samples and underwent overnight sleep-lab studies during the third trimester of pregnancy and again three months after delivery.

Eight of the ten RLS patients reported experiencing restless-legs symptoms before the present pregnancy, and all ten described worsening symptoms during pregnancy.

According to the investigators, women with RLS showed significantly higher estrogen levels during pregnancy compared to the control group. Other pregnancy-related hormone levels did not differ significantly between the two groups.

Estrogens are so-called neuroactive steroid hormones; they are important not only for conception and pregnancy but also act directly in the brain, noted Pollmächer, at the Max Planck Institute of Psychiatry in Munich.

This finding in pregnant women might help us to understand RLS in general, he said, “and ultimately lead to an additional route for the development of treatment.”

SOURCE: Sleep, February 1, 2009.