Elevated Estradiol Plasma Levels in Women with Restless Legs during Pregnancy

Study Objectives: Pregnant women have an increased risk of experiencing restless legs syndrome (RLS). Aim of this study was to elucidate the relationship between pregnancy-related hormonal and metabolic changes and RLS symptomatology. Design: Blood measurements and overnight polysomnography were performed during the third trimester of pregnancy and again 3 months after delivery. We investigated blood hormonal levels (estradiol, prolactin, progesterone, testosterone, follicle-stimulating hormone [FSH], luteinizing hormone [LH], iron, ferritin, hemoglobin) and polysomnographic sleep parameters. Subjective sleep quality and RLS symptoms were evaluated using the Pittsburgh Sleep Quality Index (PSQI) and the International RLS study group (IRLSSG) rating scale. Setting: Sleep laboratory. Participants: Ten pregnant women fulfilling the IRLSSG criteria for RLS diagnosis and 9 pregnant healthy controls underwent the protocol. Interventions: N/A. Results: Women with RLS showed higher levels of estradiol during pregnancy compared to controls (34,211 +/- 6,397 pg/mL vs. 25,475 +/- 7,990 pg/mL, P < 0.05). Patients also showed more periodic limb movements (PLMs) before and after delivery, particularly during sleep stage 1 and wakefulness (P < 0.05). PLMs decreased postpartum in subjects with RLS only (P < 0.05); sleep efficiency increased in women without RLS and remained unchanged in patients (P < 0.05). No significant differences were found between groups before or after delivery in plasma concentrations of prolactin, progesterone, testosterone, FSH, LH, iron, ferritin or hemoglobin. Conclusions: RLS in pregnant women goes along with transiently increased estradiol levels and PLM indices suggesting that estrogens play a pathophysiological role for triggering RLS symptoms during pregnancy.