Walking into classrooms at the School of Public Health, it becomes clear that the XX’s far outnumber the XY’s.

“It was most apparent when we went to orientation,” Diane Martinez EPH ’07 said. “We were joking around about the winter formal — it’s a good ratio for the guys.”

While the number of men in Yale College barely exceeds the number of women, the Master of Public Health degree program, offered through the Department of Epidemiology and Public Health at the School of Medicine, is more than 75 percent women. Only the School of Nursing enrolls more women proportionally — at 93 percent — of its student body. Though students and faculty offered a variety of opinions and reasons, ranging from the societal to the historical, as to why women are proportionally overrepresented at the School of Public Health, a consensus did emerge, perhaps best summed up by Dr. Harrison Spencer, president of the Association of Schools of Public Health.

“It’s pure speculation,” he said. “We just don’t know.”

The trend is not an isolated one, according to ASPH statistics. Women make up 69.6 percent of public health enrollment nationwide. Though Yale’s public health class is three-quarters women, nine schools in the country boast even higher proportions of women.

When the disparity between men and women in public health degree programs began is also up for debate. Spencer said women totaled 63 percent of public health enrollment in 1994, almost seven percentage points lower than they do now, but he said statistics from before 1994 were not available. Anne Pistell, dean of student affairs at the School of Public Health, said in an e-mail that the applicant pools and enrolled students at Yale’s school and others have been predominantly women for “many years.”

In the fall of 2004, Yale enrolled a class composed of 77.4 percent women. But women were only 71.8 percent of the total applicants to the school, according to the ASPH’s data. Yale officials, however, said the disparity is not significant.

“The applicant pool is the same ratio,” said Brian Leaderer, interim dean of the School of Public Health. “It’s not that one gender is more qualified.”

Though neither gender may be more qualified, some said women are drawn more to the field. It may be a stereotype that women naturally want to be in “caring” professions like public health, but some female students at the Yale School of Public Health said it holds true at times.

“In general, I feel like in any of the medical and humanitarian jobs you’re going to see a larger percentage of women because it appeals to the stereotyping of bringing up women to take care of people,” Amy Rogers EPH ’07 said.

The stereotypical role of women could help perpetuate the higher proportion of women, some said.

“Women are supposed to be all nice and gentle and look after people,” Neesha Harnam EPH ’06 said of the generalization. “Men may be more hesitant to apply to programs in public health, considering it a women’s domain, as traditionally women are perceived to be the caretakers of society.”

But the stereotype that women are inherently more capable of succeeding in the health profession, they said, is outdated.

“Anything saying women are more compassionate than males would be a sexist comment,” Janelle Anderson EPH ’06 said.

Certain aspects of public health careers that make the field more attractive in general may increase interest among women in particular, some said.

“There are life and family issues,” Erica Warner EPH ’06 said. “If you went into clinical medicine it’s not a 9 to 5 schedule, which you could potentially get with being in the public health field.”

The trend is already apparent at the undergraduate level, where more women than men seem to be interested in public health, Spencer said.

Along these lines, Dr. Uy Hoang EPH ’06, one of the few men in the social and behavior sciences track at the School, said that male applicants to schools of public health may be further along in their careers, indicating that public health may be initially less attractive to males at the undergraduate level.

Those men interested in public health may more often seek alternative routes to pursuing careers in the field, some students said. Men are most represented in the health policy and management fields, rather than the social and behavioral sciences track at Yale, students and faculty said. Students interested in policy need not study at public health schools to focus on the field, but can go to law or business school.

But the gap between men and women in public health schools could be closing. Martinez said that as more public health schools institute joint degree programs with law and business schools, male students who often are more interested in policy could enroll in public health programs. Other students said they had anecdotally heard of more men intending to pursue an MPH.

The disparity may not have much meaning for the field as a whole, some said. Jody Sindelar, a professor of epidemiology and public health, said many professors at the School of Public Health did not earn their degrees in the field, but came to it later. While Spencer said only 43 percent of public health faculty members are women, 11 of the 36 schools of public health in ASPH have female deans, and most of the associate and deputy deans are women. Women in leadership roles in public health institutes include Dr. Gro Harlem Brundtland, a recent director-general of the World Health Organization, and Centers for Disease Control and Prevention Director Dr. Julie Louise Gerberding.

More than anything, though, those who work in the field are curiously unsure why the trend continues.

“I think it’s a mystery,” Spencer said.