I assume you mean something like care professions? They don't pay less because it's mainly female workers, they pay less because they can't easily scale the generated profits.
"The ACS also reported that men are more likely to gravitate toward high-paying nursing jobs. The highest representation of men is in nurse anesthesia, a role that often pays six figures. According to the ACS, about 41 percent of nurse anesthetists are men, and their median earnings in 2011 were $162,900. Among nurse practitioners, 9 percent were men making $96,400 per year on average."
