a US charity that works to prevent the deaths of babies, to help young children born with physical problems, and to improve the health of mothers and babies. Its full name is the March of Dimes Birth Defects Foundation. President Franklin D Roosevelt, who had polio (= a serious disease of the nervous system), started the charity in 1938 as the National Foundation for Infantile Paralysis. Among other activities it supported the research work which developed the Salk vaccine. It has had its present name since 1979.