World Down Syndrome Day is observed on 21 March each year in order to raise public awareness of Down syndrome. The day is celebrated since 2012 with the recommendation of United Nations General Assembly.

• The date for WDSD, the 21st day of the 3rd month, was selected to signify the uniqueness of the triplication (trisomy) of the 21st chromosome which causes Down syndrome.
• Down syndrome gets its name from the British doctor, John Langdon Down, who first clinically identified the condition in 1866. The estimated incidence of Down syndrome is between 1 in 1,000 to 1 in 1,100 live births worldwide.
• For WDSD 2019, the theme is “Leave no one behind”.