Why is it important to get tested for sickle-cell anemia before couples ttc?

Why tested for sickl: There are carriers of sickle cell disease which is called sa or sickle cell trait.For a child to have sickle cell disease he/she has to have sickle cell trait present in both parents.Only if both parents test positive for sickle cell trait then there is one in four chance to have baby with sickle cell ss, anemia, and 2in four chances of sc, or sickle cell trait and1 in four chance normal infant.