Don't fully know, but here are some basic ideas
-More acceptable for women to work b/c more men were drafted in WW2 and there was a need for home-front help in factories = women working
-Body image changed "ideal woman." Image was partially created by Hollywood
-There was a big push for equality (19th amendment), birth control was approved in this time period, women could fight (moreso help) in war now, reference to Betty Friedan's "Feminine Mystique" might help in this.