According to a recent report by the American Psychological Association,

Inescapable media images of sexed-up girls and women posing as adolescents can cause psychological and even physical harm to adolescents and young women.

According to this APA report, the pressure of this "sexualization" can lead to depression, eating disorders, and poor academic performance. See, also, Yahoo's article on this report. What are the sources of these images? The report points to these examples:

Advertisements (e.g., the Skechers “naughty and nice” ad that featured Christina Aguilera dressed as a schoolgirl in pigtails, with her shirt unbuttoned, licking a lollipop), dolls (e.g., Bratz dolls dressed in sexualized clothing such as miniskirts, fishnet stockings, and feather boas), clothing (thongs sized for 7– to 10-year-olds, some printed with slogans such as “wink wink”), and television programs (e.g., a televised fashion show in which adult models in lingerie were presented as young girls).

It is difficult to not notice this modern smearing of the boundaries between female childhood and adulthood. Our media is obsessed with presenting images of women acting like little girls and little girls forced to act "sexualized." What's the difference between "sexualization" and healthy sexuality? According to the APA report, "sexualization" occurs when

a person’s value comes only from his or her sexual appeal or behavior, to the exclusion of other characteristics; a person is held to a standard that equates physical attractiveness (narrowly defined) with being sexy;