WASHINGTON — More medical care won’t necessarily make you healthier — it may make you sicker. It’s an idea that technology-loving Americans find hard to believe.

Anywhere from a fifth to almost a third of the tests and treatments we get are estimated to be unnecessary, and avoidable care is costly in more ways than the bill: It may lead to dangerous side effects.

It can start during birth, as some of the nation’s increasing cesarean section deliveries are triggered by controversial fetal monitors that signal a baby is in trouble when really everything’s fine.

It extends to often futile intensive care at the end of the life.

Overtreatment means someone could have fared as well or better with a lesser test or therapy, or maybe even none at all. Avoiding it is less about knowing when to say no, than knowing when to say, “Wait, doctor, I need more information.”

The Associated Press combed hundreds of pages of studies and quizzed dozens of specialists to examine the nation’s most overused practices. Medical groups are starting to get the message. Efforts are under way to help doctors ratchet back avoidable care and help patients take an unbiased look at the pros and cons of different options before choosing one.

“This is not, I repeat not, rationing,” said Dr. Steven Weinberger of the American College of Physicians, which this summer begins publishing recommendations on overused tests, starting with low back pain.

There are numerous reasons that one of three U.S. births now is by cesarean, but Dr. Alex Friedman blames some on an imprecise monitor strapped to laboring women. Too often, he has sliced open a mother’s abdomen fearing the worst, only to pull out a pink, screaming bundle.

“Everyone knows it’s a bad test,” said Friedman of the Hospital of the University of Pennsylvania. “You haven’t done the patient a big service by doing an unnecessary surgery.”

Electronic fetal monitors record changes in the baby’s heart rate, a possible sign of too little oxygen. They became a tradition — now used in 85 percent of births — years before research could prove how well they work.

Undertreatment was in the headlines over the past year as the Obama administration and Congress wrestled with legislation to get better care to millions who lack it.

The flip side, overtreatment, is a big contributor to runaway health care costs. Yet it’s one that lawmakers, wary of being accused of rationing, largely avoided in the new health care law. Included were modest steps — studies to compare which treatments work best, some Medicare financial incentives — to push higher-quality, lower-cost care.

“Physicians get up every day with the good intentions of wanting to do what’s best for their patients,” said Dr. David Goodman of the Dartmouth Institute for Health Policy. “We also live in environments where there are strong financial incentives to deliver certain types of care. We get well-paid for doing procedures. We get paid relatively poorly for spending time with patients and helping them make choices.”

Where you live plays a role. Two decades of research from the respected Dartmouth Atlas of Health Care shows that in parts of the country, Medicare pays double or triple the price to treat people with the same illnesses. The differences are not fully explained by big cities’ higher cost of living or populations that are poorer, older or sicker. How much care someone gets is a main reason, yet Dartmouth’s data shows people in pricier areas don’t necessarily fare better.

Fee-for-service care and local habits aren’t the only drivers.

Also, fear of malpractice lawsuits “has everything to do with it,” said Dr. Angela Gardner, president of the American College of Emergency Physicians.

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RELATED LINKS

Groups involved in or following issues of overtreatment include:

• American College of Physicians: http://www.acponline.org
• National Quality Forum: http://www.qualityforum.org
• American Medical Association: http://www.ama-assn.org
• National Institutes of Health: http://www.nih.gov
• Dartmouth Institute for Health Policy: http://tdi.dartmouth.edu
• Dartmouth Atlas of Health Care: http://www.dartmouthatlas.org
• American College of Emergency Physicians: http://www.acep.org
• HealthPartners: http://www.healthpartners.com/public
• Archives of Internal Medicine: http://archinte.ama-assn.org
• Foundation for Informed Medical Decision-Making: http://www.informedmedicaldecisions.org
• Annals of Internal Medicine: http://www.annals.org