There is a lot of health information available on the internet, but the unwary surfer may find him or herself less well informed or at least more confused than when she started! As with all areas of on-line publishing, there is a lot of opinion sold as fact, and you need to be aware of this when reading anything. There is a particular difficulty in the area of healthcare, as things are rarely black & white.
BALANCE OF RISKS
When making any medical decision, doctors decide whether or not the risk of treatment is balanced by the good which will come from the same. No-one inherently knows where the particular balance lies for any situation – every one is individual. What we do have to guide us is published evidence that says 'in the majority of cases this is so'. This published evidence comes from clinical trials or studies which, when properly conducted, can guide those in similar clinical scenarios.
These studies are published in medical journals who 'peer review' all that is accepted for publication. This means that they have been scrutinised by experts in the field who agree that the trial was well conducted and the results are likely to be valid (hence they may be used to guide other doctors).
Take for example a lady who is irregularly contracting at 32 weeks gestation. We know from well-organised trials that if she delivers early, her baby has a much better chance of surviving if mom is given a course of steroid injections prior to delivering. The clinical studies have been done, comparing survival in babies whose mothers were not given steroids to survival in babies whose mothers were. Of course we can't always tell which moms contracting early are likely to go on to deliver, so many might receive the treatment unnecessarily