Marthe Fohrmann and her twin sister were born on 7 May 1933 in Dudelange. His mother's name was Catherine Schumacher and his father was Jean Fohrmann. For almost 20 years, he was a socialist deputy and mayor in Dudelange. For her part, Marthe became involved in the Jeunesses Socialistes in 1948.
In 1952, she married the metal worker Jos Bigelbach. In 1955, her son André was born. In 1972, Marthe became president of the Socialist Women's section in Dudelange.
The first woman to be elected in 1974 in the south of the country, Marthe Fohrmann sat in the Chamber of Deputies for the Socialist Workers' Party until 1979. She distinguished herself mainly in the fields of social and women's policy, for example in 1978 for abortion legislation and in May 1979 when she spoke out strongly in favour of abolishing the death penalty.
From 1976 to 1988, she was a local councillor in Dudelange. In 1980, she co-founded the first crèche in Dudelange. Her cancer prevented her from continuing her political career.
Marthe Fohrmann died on 7 September 1995.