OBJECTIVE: The aim of this cohort study was to prospectively assess frequency, characteristics, and determinants of restless legs syndrome (RLS) in pregnancy and its impact on sleep.
METHODS: Pregnant women were prospectively studied in each trimester and 8 weeks postpartum. Assessments included interview about RLS symptoms and sleep disturbances; standardized sleep-wake questionnaires including the International Restless Legs Syndrome Scale (IRLSS) and the Pittsburgh Sleep Quality Questionnaire (PSQI); actigraphic recording of periodic limb movements (PLM); and blood tests including levels of hemoglobin, ferritin, and estrogen.
RESULTS: RLS was diagnosed in 58 of 501 women (12%). Positive family history was found in 37% of women with RLS; 59% reported onset of RLS symptoms before the 20th week; 45% had an IRLSS >20 and 100% had a PSQI >5. Hemoglobin levels <11 g/dL were found in 20% of both affected and unaffected women in the third trimester. Women with and without RLS had similar hemoglobin, ferritin, and estrogen levels. IRLSS and PLM in sleep dropped by more than 50% postpartum in women with RLS.
CONCLUSION: We found lower prevalence and earlier onset of symptoms compared to previous studies and confirmed significant improvement after delivery. RLS is clinically relevant due to severe impact on sleep quality. Genetic factors and smoking, but not ferritin, anemia, or estrogen levels, seem to play a role in the pathophysiology of RLS in pregnancy.