It's a fairly large research area, the effect in question is called "benevolent sexism", in which women are portrayed as being "weaker" (where the definition of weak is NOT purely physical strength) and need help to get along in life.

The interesting thing is that benevolent sexism is also widely spread in women themselves.

Here's a fairly recent paper about the spread of benevolent/hostile sexism in university undergrads, where benevolent sexism was relatively evenly spread between male and females: http://pwq.sagepub.com/content/36/4/432.full