The background:
One of the major pre-code stars is Norma Shearer, reigning queen of MGM, who persuaded the powers that be (including husband Irving Thalberg) to cast her as an adulteress in The Divorcee (1930). Shearer saw the role as an opportunity to change her image. In turn, The Divorcee was one of the first films to transform the image of the devoted wife. When her husband has an affair, Shearer's character takes matters into her own hands and has an affair of her own. On the flip side, Greta Garbo in both A Woman of Affairs (1928) and Anna Christie (1930) manages to make the vamp (and in the case of Anna Christie, the prostitute) acceptable. As Complicated Women puts it, "Norma Shearer took the ingénue into bedroom, and Garbo made the tramp moral."
Already the alarm bells were sounding among religious groups and the industry's moral watchdogs. The Hays code, which basically decreed what could and could not be portrayed in films, was issued while The Divorcee was in production.
The Production Code ruled Hollywood for thirty years and while it may have forced moviemakers to get more creative, it certainly didn't promote any sense of cinematic reality. As Complicated Women points out, the pre-code movies "set the tone for the 20th century"; the freedom portrayed in these films wouldn't reemerge until the 1960s when social attitudes shifted and consequentially the production code was lifted. It's also apparent from watching Complicated Women that terrific roles existed for women in the pre-code era, roles much richer and varied than what Hollywood offers actresses today.