A family practice physician I am acquainted with wrote the following about evidence based medicine. Reposted with her permission.
I am young enough to have trained in the era of "evidence based medicine" (EBM) where we attempt to only do those things that have evidence to back them up. In EBM, the gold standard is the randomized controlled double blinded study (RCT) Study subjects are assigned to one group or another randomly, the groups are monitored "controlled" so that you get a relatively similar type of people in both groups, and the results are interpreted by a researcher who doesn't know what group your were in, and the study subjects themselves don't know what group they are in.
This works great for a new medicine, for example, where you can make up 2 identical white pills to give someone, but not so well for behaviors. How on earth would you randomize someone to UC, and expect them not to know it? With the lack of RCTs to use, we are left with case studies, population studies, and case control studies, all of which have inherent flaws. This doesn't mean they don't provide useful information, but since they aren't randomized, you never know if there isn't something special about the group that made them choose the behavior you are studying. (For example, if only well-educated women breastfeed, and then their babies have higher IQs, it's hard to know if it's from the breastmilk, or from having better educated parents.)
The other thing that I feel is absolutely vital to remember about evidence, is that just being scientific doesn't mean there aren't belief systems attached to that evidence. Why do things get studied in the first place? Who pays for it? Who benefits or is harmed by results? There is no "evidence" that is completely objective. It isn't "science" vs. "belief"; science is just another type of belief.
I do not suggest that we need to ignore what evidence we have, but an individual will always need to make his/her own decision also taking into account their beliefs, values, background, relationships, fears, etc. Just because someone does something that seems to go against "evidence" doesn't automatically mean they are making a bad decision. I encounter this every day in my family practice. Sometimes, I have great evidence based reasons for wanting to offer a certain treatment, but my patient has even better life based reasons for declining it, or doing something else.
Even if the evidence were ever to come to light that intentional UC isn't as "safe" as another type of birth, there may well be highly intelligent people who continue to choose that type of birth for their own reasons. Having no such evidence at this point (or in all likelihood, such evidence may never be available) women will continue to make their decisions based on evaluating what evidence there is and taking into account the many other areas of their lives that are impacted by birthing choice...
And a clarification of some of the earlier points she made:
[It is important] to consider how evidence is collected, whether it has relevance to the situation you yourself are considering, and whether it is accurate. Also, it is vitally important to remember that although in the age of evidence based medicine, we purport that "evidence" is somehow completely objective, in reality it is not, nor can it ever fully be disconnected from the social constructs from which it arises. Science and even "evidence based medicine" are themselves belief systems. I happen to live in the world where evidence is very important, and I try very hard to stay on top of the latest and greatest, and I very freely share every bit of evidence I'm using in making a recommendation with my own clients. But I also recognize that evidence will never be the sole factor in any decision made by a real person, nor should it be, nor should I feel any personal discomfort if someone receives my knowledge of the evidence, and chooses to do something other than what I recommend.