In today's world, movies are much more lenient about censorship then they were in the past. What might have earned a rating of R in 1970 could be PG-13 today. How did censorship affect films in the past?
When the film makers were adapting a literary work such as a novel or a play to the big screen, any swearing was often toned down. This is somewhat noticeable in the differences between George Bernard Shaw's 1913 Pygmalion: A Romance in Five Acts and the 1938 film Pygmalion (though it is less noticeable in the 1964 My Fair Lady). One may notice that the film version cuts a few "damns," "hells," and "bloodys" from the original source material. It does not really interfere with the production, so such censorship is acceptable.
However, some forms of censorship change entire plotlines. For example, in the 1951 film A Streetcar Named Desire, in order for the rape scene from the original 1947 work to remain intact, it was decided that Stanley (Marlon Brando) had to be punished for it. This resulted in a slight rewrite of the ending. Instead of coming back to him as always, Stella (Kim Hunter) realizes that Stanley is responsible for Blanche's (Vivien Leigh) madness and leaves him. Of course, whether she returns or not at his first calling is up for the viewer to decide, but it is an example of censorship changing the outcome of a story.
Finally, one thing that was not acceptable in the past in films was showing pregnancy. A film could not show a woman physically pregnant. This is seen in the end of the 1939 film Wuthering Heights. Instead of being pregnant and about to die like in the novel, Cathy (Merle Oberon) is near death due to illness. In Brontë's 1847 novel, the delivery of her child before her death is the beginning of the second part of Wuthering Heights; however, in the movie, due to time constraints, the second part could not be covered. In this instance, the censorship was somewhat convenient because Cathy was not going to produce a child to prolong the movie. This form of censorship was also noticeable in A Streetcar Named Desire; Stella, was carrying Stanley's child, did wear smocks but they did not bulge enough to make her "look" pregnant.
While these forms of censorship are practically unheard of today, the world of the past seemed to live on a
different, stricter moral code. Although at times, this censorship did not adversely affect some movies, it often hindered the more daring attempts of serious film makers.