I would like to address the false dichotomy you have indicated - that it doesn't make sense to talk of people being diverted from software development into health care fields. There are a couple of essays I'd suggest. Neither are about programming or women - they're about science/engineering graduate programs and Americans. However, they both reach the conclusion that Americans in general are rationally avoiding graduate degrees in STEM fields.
The first is a study by the RAND institute:
http://www.rand.org/pubs/issue_papers/IP241.html
This study concludes that Americans are avoiding STEM degrees in large part because the pay and job prospects compared to the "professions" including law or medicine have become so uncompetitive.
Another is by professor William Zumeta at the University of Washington. He looks into students with strong quantitative backgrounds to analyze why they are not going into science and engineering. He does conclude that they are often going to MBA or Health Sciences. (He also does address some systemic problems that particularly affect women in these fields).
http://www.issues.org/19.2/p_zumeta.htm
Unfortunately, these researchers don't really address the false dichotomy you've brought up - they seem to assume that academically talented students do choose between very different fields based on pay and career prospects. Perhaps that is, as you've suggested, a deeply flawed assumption.
Believe it or not, I actually think that this in no way invalidates claims that outright discrimination or socialization from an early age is a factor! After all, even if it is a relatively poor career choice (already a very debatable claim), these can still be substantial (even definitive) factors!