Very good question, but hardly believe to find a concrete answer to it. May be there is a psychological factor or a stereotype of certain proffesions why women prevail... To be more exactly why men do not prefer them.

Agreed, which is why I hope it makes/made for an interesting research question too :)

The problem is what kind of data and research methods to be used for answering to that question. Questionnaires? Official statistics?

This questions has been looked at some within economics and demography. Search under the term `occupational segregation' and you may get more answers. For a start see, Charles, Maria (2003). "Deciphering Sex Segregation: Vertical and Horizontal Inequalities in Ten National Labor Markets". Acta Sociologica (46): 267–287.

@Ujvala: Thanks for the reference :)

@Cimpoies: The areas that I've mentioned are organised sectors in most parts of the world. So an estimation procedure may be applied to assess the gender distribution in any one profession. Similarly, an estimation can be arrived at for the per capita earning in each profession, which can be compared with the per capita earning in professions where more males prevail. Just a thought, but I'd like to know what you think too.

There are a lot of papers which estimate the effects of occupational segregation within each establishment on the wage gap. Most of them shows that the greater the proportion of women in a particular job, the lower its wage. Morover, the greater the proportion of women within each job, the greater the wage difference between men and women. For example, you can have a look at Kyra and Korkeamaki´s paper, published in Labour Economics in 2006. You can get a lot of references from this paper.

Miguel, thanks for the references; they're a huge help :)