Pregnancy: Risk for Restless Leg Syndrome

Sept. 27, 2004 - New research shows that pregnant women are more likely to get a sometimes painful condition that interferes with sleep -- restless leg syndrome.

Restless leg syndrome (RLS) is a movement disorder, which causes an urge to move the legs, associated with an uncomfortable or unpleasant sensation. People with the disorder describe the sensations as pulling, drawing, crawling, wormy, tingling, pins and needles, prickly, and sometimes painful sensations. Sudden muscle jerks may also occur.

Symptoms usually worsen in the evening or at night and are relieved by moving the legs.

The condition, which becomes more common with age, affects 5%-10% of the population.

Mauro Manconi, MD, of the Sleep Disorders Center at Vita-Salute University in Milan, Italy, and colleagues, studied pregnancy and restless leg syndrome using a recently revised international definition of the condition. While the cause of RLS remains unknown, many conditions have been linked to RLS -- including pregnancy.

Pregnancy was first linked to restless leg syndrome in 1940, with a few other studies confirming the connection.

Nearly 600 Italian women participated in the study, which assessed symptoms from the beginning of pregnancy. Within two days of giving birth, the women talked to a pair of neurologists certified in sleep medicine.

During the next six months, researchers followed up with those who reported having restless leg syndrome during pregnancy.

More than 26% of the women were affected. For most, it was their first time experiencing the condition.

Nearly 25% had at least one episode a week, and almost 15% reported three or more weekly episodes.

As a result, the women slept less, had more insomnia, and were more likely to be excessively sleepy during the day.

Worse in Third Trimester

Cases peaked in the third trimester of pregnancy, particularly in the seventh and eighth months of pregnancy.

For most women, restless leg syndrome went away after giving birth. One month after delivery, only 7% of the group had restless leg syndrome.

Potential Causes

One possible reason for restless leg syndrome was that affected women were more likely to have lower indicators of stored iron.

However, women lose blood and iron in giving birth, and it takes nearly three months for levels to return to normal. During that time, restless leg syndrome improved. The researchers also saw that no differences existed with iron or folate levels between healthy women and those who suffered from RLS.

Another theory blames hormones.

"The rapid and important restless leg syndrome improvement after delivery gives more power to the hormonal rather than to the iron hypothesis," write the researchers in the September issue of the journal Neurology.