Restless legs syndrome (RLS) is a multifactorial disease that patients describe as restlessness in their legs, which creates a desire to move their legs, especially in the evening and at rest. This study aims to investigate serum selenium levels in RLS and document the quality of sleep and life in pregnant women with RLS according to International Restless Legs Syndrome Study Group (IRLSSG) diagnostic criteria. Thirty-eight moderate to severe RLS patients with pregnancy at 38–41 weeks of gestation were determined as the case group, and 38 women with healthy gestational age-matched pregnancies were determined as the control group. Maternal serum selenium levels were compared between the RLS case group and the group of healthy pregnant women at the time of hospitalization for delivery. The Pittsburgh Sleep Quality Index (PSQI) and The Quality of Life Scale (SF-36) were applied to the patients. The mean selenium level (µg/L) was statistically significantly lower in the RLS group (53.24 ± 10.28), compared to the healthy pregnant population (58.95 ± 11.29) (P = 0.024). The PSQI score was significantly higher in the RLS case group (P = 0.033). Especially sleep efficiency (P = 0.018) and daytime dysfunction (P = 0.032) sub-parameters were affected. The SF-36 questionnaire was examined and a significant difference was detected between the two groups in role emotional (P = 0.026), social functioning (P = 0.023), and body pain (P = 0.044) sub-parameters. Serum selenium level was significantly lower, the sleep quality of the RLS group was impaired and their quality of life was affected in pregnant women with RLS. Further studies are needed to determine whether selenium replacement in pregnant women with RLS is feasible or not.