The L-Shaped Room, Lynne Reid Banks’ 1960 novel about the pregnancy of a young (ish) single mother, is a superb evocation of a time when women’s choices were limited and attitudes to sex and marriage had not yet been challenged by the ‘permissive’ 1960s.
Single mothers in the 1950s and 1960s faced prejudice and opprobrium, and were advised to hide their shame by pretending to be married or widowed. You could choose to confer a kind of legitimacy on the child by legally adopting it and giving it your name.