On this day (May 1) 55 years ago, LIFE published Lennart Nilsson’s groundbreaking photo essay “The Drama of Life Before Birth.” It was the first-ever photographic fetal development timeline, featuring children of varying ages after they were miscarried or aborted. 

To capture the images, Nilsson worked closely with the head of a women’s clinic at a hospital in Stockholm, who would call him within hours of an unborn child’s death so he could come in and photograph them. Only one of the images (the third photo here, on the spread that says “The Drama of Life Before Birth”) features a living child, 15 weeks old; it was taken with a wide-angle endoscopic camera. This image was the first published photograph of a fetal human being taken inside the womb.

In an article in The Guardian, Charlotte Jansen describes the now-iconic magazine cover: “In full colour and crystal clear detail, the picture showed a foetus in its amniotic sac, with its umbilical cord winding off to the placenta. The unborn child, floating in a seemingly cosmic backdrop, appears vulnerable yet serene. Its eyes are closed and its tiny, perfectly formed fists are clutched to its chest.”

Nilsson considered himself apolitical. He took these photos without any abortion-related agenda in mind. However, these photos revolutionized the way people see life before birth, and whether Nilsson intended them to or not, they rehumanized the tiniest members of our human family. #prolife #onthisdayinhistory