Author of the genre and satire verses (collections: Song of the province / Sange fra provinsen, 1913—1921; Wide Wings, 1919; Songs for all the Winds, 1927).
His novel Factory of the Saints (1919, Russian translation 1924) became a prototype for Yakov Protazanov's 1930 film St. Jorgen's Day — a satire on the church and its ministers' hypocrisy.
Before the Second World War, he was a social democrat and was an immensely popular poet.
Several still popular Danish children's songs have lyrics by Bergstedt ("Hør den lille stær", "Solen er så rød, mor",[1] "Jeg ved en lærkerede").
In 1948, he published a verse collection named Songs in the Jail with his thoughts on his life and works.