Background
She was born in Kristiania as a daughter of captain and engineer Anton Martin Schweigaard Nicolaysen (1870–1907) and Dorothea Jeanette Horn (1870–1943).
She was born in Kristiania as a daughter of captain and engineer Anton Martin Schweigaard Nicolaysen (1870–1907) and Dorothea Jeanette Horn (1870–1943).
She finished her secondary education at Frogner School in 1915, and graduated as a teacher from Nissen School in 1916.
She was a niece of Hassa Horn and a grandniece of Hassa Horn, Senior
The family moved around in Norway a lot, among others to Harstad and Eidsvoll. Engelhart became active in the Norwegian Housewives" Association (from 1997: the Norwegian Women and Family Association), and after the occupation of Norway by Nazi Germany when she housewife association work had largely been abandoned, Engelhart took the helm of the whole organization in 1946, chairing it until 1959. From 1956 to 1960 she chaired the Nordic Housewives" Association.
She chaired the United Nations Association of Norway from 1948 to 1952, and was active in Foreningen Norden and Landsforeningen Norsk Arbeide.
She died in August 1984 in Oslo.
Engelhart was also a member of several committees and councils to improve housework and domestic science, and she was a board member of the Norwegian National Women"s Council.