WASHINGTON — Sandwiched between a swimming pool store and a spice shop in Fairfax, Va., the Tepeyac Family Center looks like any other suburban doctor's office. But it isn't.

The practice combines "the best of modern medicine with the healing presence of Jesus Christ," a brochure at the reception desk announces. An image of the Madonna greets every patient. Doctors, nurses and staff members gather to pray each day before the first appointments.

The center is one of a small but growing number of practices around the country that tailor the care they provide to the religious beliefs of their doctors, shunning birth-control and morning-after pills, IUDs and other contraceptive devices, sterilizations and abortions, as well as in-vitro fertilization. Instead, doctors offer "natural family planning," teaching couples to monitor a woman's temperature and other bodily signals to time intercourse.

Proponents say the practices allow doctors to avoid conflicts with patients who want services the practitioners find objectionable, as well as to provide care that conforms with many patients' own values. The approach, they say, provides an alternative to mainstream medicine's reliance on drugs and devices that, they argue, carry side effects and negatively affect couples' relationships.

"I want to practice my faith," said John Bruchalski, the obstetrician-gynecologist who started Tepeyac. "I'm not interested in pushing it on other people. But this allows me to practice medicine without having to do something that I wouldn't see as positive or healthy."

Critics, however, worry that the practices are segregating medicine along religious lines and may be providing inadequate care by failing to fully inform patients about their options. The critics are especially alarmed about the consequences in poor or rural areas with few alternatives.

"Welcome to the era of balkanized medicine," said Alta Charo, a bioethicist at the University of Wisconsin at Madison. "We've had this for years with religious hospitals. What's happening now is it's drifting down to the level of individual practitioners and small group practices. It essentially creates a parallel world of medicine."

The American College of Obstetricians and Gynecologists has no formal position on such practices, but its officials say the approach can offer a way for religious doctors to work and serve religious patients as long as they are up-front about their limitations.

"If women know before selecting them, then it's quite a legitimate thing to do and might meet the needs of many women and doctors," said Anita Nelson, of the University of California at Los Angeles, speaking for the organization. "But if you hang out your shingle that says 'All-purpose OB-GYN' and don't offer certain services, that's false advertising."

The phenomenon is another manifestation of the tensions arising between religion and medicine with the rise of religious expression in the United States and medical advances that create moral dilemmas for some. Natural family planning, or NFP, practices are seen as a way of sidestepping confrontations over abortion, the morning-after pill and other types of care that some religious health workers refuse to provide, asserting a "right of conscience."

"This is a way that some of us have found to practice medicine that is consistent with our beliefs," said Kathleen Raviele, of the Catholic Medical Association, which, along with groups such as the American Association of Pro Life Obstetricians and Gynecologists, promotes natural family planning.

"It's definitely a new trend, and it's a refreshing trend," said Theresa Notare, of the U.S. Conference of Catholic Bishops, which has workers in at least half its dioceses trying to enlist more doctors to open such practices. "This is a trend that we should be excited to see grow."

The number of "NFP-only" practices is unknown, but an Ohio-based Web site promoting them has a registry of nearly 500 doctors who have pledged to practice this way. Most are obstetrician-gynecologists and family practitioners.

Doctors on the registry say they converted their practices after struggling to reconcile their beliefs with their medical responsibilities, often after years of being penalized or shunned by colleagues.

"I've encountered a lot of resistance to how I practice over the years," said Lorna Cvet-kovich, an obstetrician-gynecologist in Ann Arbor, Mich. "For one thing, contraception and sterilizations bring in a lot of revenue. But I finally found partners who feel the way I do, and we're scraping by."

Some women, however, report being dismayed after stumbling into one of these practices without realizing what they were.

"It never crossed my mind that it would be an issue," said Katie Green, 26, who was refused a birth-control prescription. "I was really irritated. It just rubbed me the wrong way."

"It caught me completely off guard," said Elizabeth Dotts, 25, who had a similar experience in Birmingham, Ala. "I felt like he was judging me and putting pressure on me. ... I am the patient. I am the client. It should have been about me — what I needed. Not what he needed or believed."

Some experts say such practices are providing substandard care if they do not fully inform patients about all options.