Marie-Pier Normand Lejeune was arraigned by telephone in her hospital bed in Alma, Que.
Provincial police said the woman was transported to hospital by ambulance and showed signs of a recent delivery, but had no baby.
Officers later found the newborn early Friday at a home in Metabetchouan-Lac-a-la-Croix, about 225 kilometres north of Quebec City.
Police say the 22-year-old woman was formally arrested on Sunday and will remain detained.
Her lawyer did not say whether she intends to seek bail and the case is scheduled to return to court in early March.