You might think medical guidelines are based on years of clinical evidence and gold-standard research. After all, doctors use them every single day to make life-or-death decisions.

In reality, they're based on the whims and fancies of the medical elite... and that's especially true when it comes to women's health.

A new study finds that nearly a third of 717 practice recommendations issued by the American College of Obstetricians and Gynecologists are based solely on expert opinions -- with another 38 percent driven by the kind of weak observational studies I'm always warning you to take with a grain of salt.

All told, just 30 percent of the guidelines obediently followed by 50,000+ ACOG doctors are based on gold-standard clinical trials.

That's it.

In other words, there's not a lot of "evidence" in the "evidence-based medicine" touted by the mainstream. But it does help answer some of the questions I've had about ACOG.

This is, after all, the same group that issued a defiant new call for more frequent mammograms -- despite solid evidence that those screenings have led to the mass overtreatment of benign tumors. (Read about that here.)

Those guidelines have punished a generation of women with disfiguring mastectomies and toxic radiation -- but as I've told you before, they've barely made a dent in the breast cancer death rate. (Read the story here.)

ACOG isn't the only group issuing guidelines despite a lack of clinical evidence to back them up: One study earlier this year found that six out of seven guidelines issued by the Infectious Diseases Society of America had no solid research behind them.

That's why docs were told to pump patients full of antibiotics the moment they even suspected pneumonia in a patient -- a practice that fueled the overuse of the meds and helped breed drug-resistant superbugs... without actually improving outcomes.

And in even more outrageous cases, guidelines are written under the watchful eye of "experts" with a direct financial stake in the outcome -- like many of those issued by the American Heart Association and American College of Cardiology between 2003 and 2008. (Read about it here.)

Put it all together, and the sad reality is that the deck is stacked against you before you even set foot in the doctor's office -- and that's why whenever your doctor gives you a treatment, you need to stop and ask him why before you follow his orders.

I'll have more on the questions you need to ask during any trip to a doctor later this week.