Last Sunday, at 10:40 a.m., Laura McCullough became a doctor. Ninety-six other graduates of the University of Vermont's College of Medicine also received their M.D.s, the culmination of years of hard work, long hours and hundreds of thousands of dollars. Sixty-two percent of those graduates were female, making this the largest number of women ever to graduate from UVM med school.

That number is not an anomaly. For nine of the last 10 years, female medical students have outnumbered males at UVM. "We like to think we're leading the way," says John Evans, dean of the College of Medicine. Evans joined the faculty in 1976, when fewer than 15 percent of the graduates were women. "I'd have to say that it's the single greatest demographic change in medicine," he says. "It's a national trend, but we've been ahead of the curve for a while."

Women now account for roughly half of all medical school students, even at historically male strongholds like Harvard. Nationwide, the number of women physicians has increased eight-fold since 1970. In Vermont, the statistics are similarly striking. Although women still account for only 29 percent of all physicians in the state, the number is up 7 percent from just two years ago, and climbing rapidly: Eighty-nine percent of all doctors over age 55 in Vermont are men; only 44 percent of those under 35 are.

This trend has merited its own moniker in medical circles -- "the feminization of medicine" -- but the general public has barely seemed to notice. Most people, except perhaps the elderly, are no longer shocked to be treated by a woman. But they might be surprised to learn that at UVM, women med students are more likely to go into urology than men are to become obstetricians. Or that Gen X and Y doctors -- male and female alike -- work far fewer hours than their predecessors, largely because women physicians have demanded a more balanced lifestyle and forced open the door to part-time work.

What impact is the influx of women physicians having on health care? More than anyone would imagine.

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The notion that there may be fundamental differences between the sexes can be a political minefield in education, as Lawrence Summers, the former president of Harvard, learned too late. Summers succumbed to faculty pressure and resigned in February after asserting that innate differences between men and women could help explain why women lag behind in science and math careers. Certainly no one is saying that with regard to medicine. Yet some reflexively bristle at the open discussion of differences in practice styles between men and women.

Nevertheless, in March 2005, an online newsletter of the New England Journal of Medicine tacitly acknowledged the distinction when it chose to reprint a Chicago Tribune article stating, "Medicine is generally becoming more patient-friendly, treatment is improving, and malpractice suits may become less common" because of the presence of women.

"I do think females bring a softer side to medicine," says recent UVM grad McCullough; her perception is echoed by many physicians around the state. While administrators at UVM stress that communication skills are more likely to be determined by personality than by gender, research published in the Journal of the American Medical Association (JAMA) indicates that women physicians typically spend more time communicating with patients. They are also more likely to discuss the emotional influences on a patient's health. As a result, patients are less likely to sue when things go wrong. Women do have statistically fewer malpractice suits than men.

And for whatever reason, women draw more patients into a practice. "There is a huge demand for women doctors," declares Lori Leo, the owner of the New England Physician Recruitment Center. "Patients, and practices, are looking for women."

The repercussions in health care are profound. Women are twice as likely to go into primary care -- welcome news for the specialty of family practice, which has been on the verge of collapse. U.S. News & World Report recently ranked UVM in the top 15 percent of U.S. medical schools for primary care. In large part, that's due to women students. In the last three years, 14 women, but only two men, at UVM have chosen a career in family medicine. More women than men have also opted for internal medicine.

Women physicians tend to cluster in specialties such as obstetrics and pediatrics as well, which is more good news for women and children. But it's a potentially worrisome trend for a country full of aging baby boomers who are more likely to need orthopedists, pulmonologists and cardiologists in years to come. (Vermont is the second-oldest state in the union.) According to JAMA, the number of practicing pulmonologists is expected to drop over the next 25 years, while need for them will increase by 66 percent; cardiology has similar figures. Many experts think this is due in part to the increase in women doctors.

"We also don't see a huge number of women in medical school going into demanding surgical subspecialties," says Elizabeth Jillson, a clinical associate professor at UVM and part-time Essex pediatrician. Given that 35 percent of doctors currently practicing in the state did their med school or post-graduate training in Vermont, what happens at UVM is particularly relevant to the future of Vermont health care. Since 2003, only six women at UVM have chosen to specialize in general surgery. On the other hand, during the same period 34 women chose pediatrics; 18 went for obstetrics/gynecology.

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Why are women avoiding certain fields? The average age of a first-year UVM med student is nearly 26. After completing four years of school, women thinking about having families may be inclined to limit additional training to the three years needed to become a pediatrician, internist or family-practice doctor. Training to become a surgeon or to enter some specialties takes five-plus years.

Debra Gargiulo, a 2005 graduate of UVM's College of Medicine, is an exception -- she chose a career in general surgery. But Gargiulo was already an atypical student. A math teacher in inner-city Boston for 20 years, she began med school at age 40. With 50 percent of her classmates women, Gargiulo wondered why only 5 percent were going into surgery. As part of a senior year research project, she surveyed surgery and obstetric/gynecology attending physicians, residents and third- and fourth-year medical students about their choice of specialty. Her findings were published last month in the journal Archives of Surgery.

"I started with the hypothesis that women didn't go into surgery because they didn't have an identifiable role model, or that they were choosing not to go into surgery because of lifestyle," says Gargiulo. "But that didn't explain why they were choosing to go into obstetrics," which also has long, unpredictable hours. Instead, Gargiulo found that it was the "surgical personality" that was turning many women off. In the comment section of the survey, one student mentioned the chauvinism of some of the surgeons and didn't want them as colleagues. Others -- men and women -- echoed that sentiment. (Gargiulo did add that while surgery as a whole is viewed as chauvinistic and hierarchical, UVM is generally considered benign in this regard.)

Change will no doubt come as more women assume academic leadership positions. Gargiulo tells the story of a family friend, now in her eighties, who applied to a prestigious medical school and was told she could sit in on classes to "appease her curiosity," but that she could not get credit. Accepted elsewhere, she went on to become a brilliant pediatric cardiologist. "Now we can laugh at that," says Gargiulo. "Hopefully, down the line, we'll also laugh that one day we were worried there weren't enough women in administrative roles or in surgery."

That day may come sooner rather than later. In 2003, the chief of surgery at Johns Hopkins was asked to speak at UVM. She recounted for the students how her 6-year-old son had recently posed a wonderfully innocent question. "Mom?" the little boy asked, "can boys become surgeons, too?"

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Even in specialties where chauvinism is no longer rampant, a career in medicine can present serious obstacles to women in their twenties or early thirties. Nathalie Feldman, an Essex Junction obstetrician/ gynecologist, entered medical school in 1983 with a confident, can-do attitude. With an undergraduate degree from Yale and an M.D. from McGill, she was on the fast track to a prestigious career. She even published numerous research articles in her early residency years. In the third year, she and her husband, also a physician, decided to start a family.

Life as an OB/GYN resident involved staying all night at the hospital every third night. "I vowed that no one would have to do more call because I was having a baby," says Feldman. Once her daughter was born, Feldman would often have her brought to the hospital parking lot between clinics so she could nurse her.

"It was a brutal schedule and a constant struggle to find time to be with the baby," she says. Finally, after the birth of her second child and nine years of private practice, Feldman decided to cut back. In 2001, she ended her partnership arrangement and stopped her obstetrics and surgical practice entirely. She now sees patients as an employee of her former partners and works two or three days a week.

Feldman is hardly alone in her decision to reduce her hours. According to numerous national studies, gender is a strong predictor of part-time work. Of course there are plenty of female workaholics, women who put in longer hours or more days than their male counterparts. According to the 2004 Physician Survey conducted by the Vermont Department of Health, women surgeons put in the longest hours of anyone in any specialty, male or female. Nevertheless, the Council on Graduate Medical Education, a government-sanctioned oversight committee that assesses physician workforce trends, has cited extensive research showing that women physicians typically work fewer hours than male physicians, largely due to family responsibilities. Physician Executive magazine reports that some hospitals discount the economic benefit of a female physician's labor at .8 FTE (full-time equivalent) of the full-time week for male physicians when estimating staffing needs.

While this may seem discriminatory, no one is accusing women of being lazy. Hospitals often consider full-time for physicians to be 60 hours, so someone working .8 FTE is still putting in at least a 40-hour workweek. Jonna Goulding, a family practitioner who shares a practice with her husband at Randolph's Gifford Medical Center, is a textbook case. Considered .75 FTE, she nevertheless puts in 40- to 50-hour weeks. (Her husband also works part-time in the emergency room.) "My children don't want to pursue a career in medicine," says Goulding. "They say we work too hard."

But in primary care, 60-hour work weeks are routine. The unavoidable demands of a practice -- dictating medical charts, required medical education courses, credentialing, after-hour patient calls, board exams, office meetings, committee work, insurance paperwork, hospital and nursing home rounds -- make actual face-to-face time with patients a surprisingly small part of a physician's day.

Laws have been passed in recent years that limit residents to working 80 hours per week. But the culture of certain specialties, particularly surgery, can be exceptionally demanding. Surgical residents routinely ignore the rule. "It would take a really tough person to say, 'I'm going home,'" says Jillson. "They're supposed to die with their boots on."

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Twenty years ago, a part-time physician was almost unheard of. But as more women enter the profession, their desire to balance work and home life has caused a seismic shift in practice patterns. According to the 2004 Physicians Survey, only 36 percent of women physicians in Vermont -- and 53 percent of men -- now provide patient care 40 or more hours a week.

"The half-time option started out with women wanting to combine career and family," explains Dayle Klitzner, a part-time family-practice doctor in Middlebury. "And then society changed, and now it's more acceptable for men to work part-time, too. It's now a lifestyle choice."

Ask physicians who have been in the business for 20 years or more and they'll say the younger generation is generally unwilling to work the long hours of the past. If the Vermont survey is accurate, between 2002 and 2004 the number of doctors putting in more than 40 hours per week of patient care dropped by 12 percent, while the number working fewer than 30 hours increased by 24 percent.

Some older physicians worry that by working part-time, doctors are denying patients continuity of care. Others, who missed the birth of their baby or rarely got to see a child's softball game, are more supportive.

"The new generation is much less driven to work long hours, even in their specialty choices," acknowledges Nathalie Feldman. "They're going into emergency medicine, or anesthesia, where you have to work but there's no call. They have a much clearer sense of what their priorities are going into it than I did."

Medical schools have become more accommodating. Most now routinely grant maternity and paternity leaves, a big change from 20 years ago when a student who gave birth was expected to return to work two weeks later. Even students like Laura McCullough, who plans to work full-time after med school regardless of family demands, can benefit from the change in attitude. "I have a quarter of a million dollars in debt," says McCullough. "Part-time is not a reality for me." She also points out that residency programs now flaunt family-friendly policies as a way to attract graduates.

The rules governing tenure in academic institutions are also changing. Once limited to those who completed training requirements within a certain number of years, tenure is now more often based on accomplishments regardless of time limits. As a result, women who take time off to raise children are no longer effectively barred from reaching positions of academic leadership. Although women are still woefully underrepresented in top positions -- only 10 percent of med school deans are women -- they will no doubt make real strides over the next decade.

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Maternity and paternity leave, humane work hours -- these seem like positive developments. Yet a glaring question remains: Who will take care of the patients? Simple mathematics dictate that as doctors work less and an aging population needs them more, a shortage of physician hours could lead to a health-care crisis.

A 2002 article in Health Affairs, a leading health-policy journal, predicted that by 2020 there will be 200,000 too few physicians in the United States; more conservative estimates puts the shortage between 65,000 and 150,000. Such forecasts are especially startling given that not long ago the medical community was predicting a doctor surplus. That never materialized, some say because so many physicians have chosen to work fewer hours.

Other factors contribute to the impending shortage. Medical economists point to everything from baby-boomer retirements to the premature departure from the work force of physicians frustrated by long hours, rising practice (and malpractice) expenses, and problems with Medicaid and Medicare reimbursements.

A career in medicine is also not as lucrative as it once was; finance or business now has a much greater potential for a big payday. The "feminization of medicine" may be to blame. It's a harsh economic reality that when women enter a profession in large numbers, the pay tends to go down. "You really want to know what I think the biggest change will be?" Klitzner asks. "We're going to get paid less. I know it sounds cynical, but there will be less reimbursement and less prestige."

Last year the American Association of Medical Colleges acknowledged the looming shortage and called on all medical schools to admit 15 percent more students; now it is considering boosting that recommendation to 30 percent. Entirely new medical schools are also under consideration in seven states.

UVM's med school increased its enrollment 20 percent six years ago, and Dean Evans says that a further increase is possible at some point if the same quality of education can be ensured. "We would have no trouble filling additional spots," he says. "The most difficult thing is that so many highly skilled and qualified students are turned away."

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There may be an upside to having more doctors working fewer hours, and not just for the physicians and their families. "Patients don't want doctors who are burned out," says Jennifer Shu, a part-time pediatrician at Dartmouth-Hitchcock Medical Center in Lebanon, N.H., and an unapologetic proponent of the new order. "They want someone who is happy and fresh and enjoys working."

Many of the physicians who are now working part-time say they are likely to stay in practice longer because they like their schedules. Many feel that time off is more valuable than money, especially in places like Vermont where the cliche has always been that half the pay is in scenery. "I can see myself working part-time for a long time," says Klitzner. "If I were slaving away, I'd be thinking about retirement."

Another unexpected benefit may be that physicians will get creative with their schedules. "They will do shift work, flex time, work on evenings or weekends," says Shu. "It's no longer a 9-to-5 world. We can meet parents after hours so they don't have to miss work every time a kid is sick."

P.A.s or nurse practitioners may also fill some gaps. Hospitalists -- physicians whose practice is limited to the care of hospital patients -- could make primary-care practice less onerous. Technology may blunt the effect of fewer full-time workers, with email making physicians more available for questions and electronic medical records allowing access the latest information on any patient.

Yet no matter how many computers are enlisted, the human variable remains. To help prevent shortages in certain specialties, women will likely need to look beyond internal medicine, pediatrics and obstetrics. And those in traditionally male-dominated specialties are going to have to determine how to attract more women to those fields. "If a large percentage of people don't want to enter surgery because of 'the surgeon personality,' the specialty should look at itself and see what it can do about it," says Shu. "It would behoove them to try to change the culture to make it more appealing."

Despite the recent emotionally charged debate in academia about female aptitude for the sciences, women seem to thrive in medicine, even in traditionally male environments such as surgery. "The surgery attendings I work with say the female residents are the strongest," says Gargiulo, who now works at Baystate Medical Center in Springfield, Mass. "They say they have a better bedside manner, and they are more ambitious and more conscientious." Certainly, if surgery is not to remain a male bastion, women have to start making the choice to pursue it.

"Things have definitely changed since I was in medical school and being a female physician was a pioneering thing," says Paul Jarris, Vermont's commissioner of health. "When women first became physicians they had to show they were as tough as a man. But we have reached a point where women don't have to do that anymore. That can work to the benefit of all of us."