Yeah, I'm in that field, ie. computing.

Back when "programming" was 1% programming and 99% feeding punch cards into massive mainframes, it was dominated by women. Men overwhelmingly designed and built the machines, but women were the bulk of the employment in the field because writing the simplistic programs and feeding the cards in was largely pitched as secretarial work.

As programming became more involved and extensive, and programming languages evolved, the largely unskilled aspect of the labour disappeared and it became a professional industry. Those entry level, low-skill jobs disappeared, and took the women with them.

Did they lose the jobs because of their sex, or because they were unskilled labour? Did the pay increase because of incoming men, or due to the rise of education and skill necessary to do the job? My Mom taught herself Fortran and Cobol and survived. Most opted not to, and left the industry.

Any other examples?