Grethe Heltberg was born in eastern Jutland as the daughter of a teacher, passed the upper secondary school leaving examination, worked as a parliamentary stenographer, and later became a housewife. One of her three children is the author and journalist Bettina Heltberg.
Grethe Heltberg made her debut in 1942 with her poetry collection Portræt af en Pige. Her other works include Alle mine søstre, 1976, a poetry selection, and Pige fra provinsen (M), 1969, En jomfru fra Jylland (M), 1969, and Vi, (M), 1971, followed by the memoir of her mother, En gnist af glæde, 1975. She also wrote novels, short stories, and essays. Her works have a serious tone arising from the tension between awareness of death and the vivid present moment, as experienced in love and children.