During the interwar period he made a significant but controversial social effort to help women of limited means with sex education, birth control and abortion.
In the 1920s he was known to the public through his agitation for better sex education, safe and affordable contraception and better access to abortion, particularly for poor families with many children.
In 1924, together with writer Thit Jensen he initiated Foreningen for seksuel Oplysning (Organization for Sexual Awareness), which worked for women's right to use birth control, in particular the diaphragm.
[7] As part of the sexual liberation, induced abortion was made legal in Denmark in 1973, and much of what Leunbach originally fought for is now regarded as self-evident rights.
Leunbach is mentioned in episode 10 of the Danish TV series Matador, where in 1935 one of the leading ladies creates a commotion in the town by supporting his thoughts on abortion.