Restless legs syndrome (RLS) is common in the third trimester of pregnancy. In this case–control study, 22.5% of 211 women had RLS. The RLS cases had a history of growing pains (GP) more frequently than controls (P = 0.042). A family history of GP (P = 0.025) and RLS (P = 0.018) was more frequent among cases than controls. RLS in pregnancy is predicted by family history of RLS and GP, and by childhood history of GP.