Pregnenolone has been around since the 1940s and is a precursor to other steroids (it is like a parent and the offspring are testosterone, etc.....). It is being promoted as a cure-all or a help-all. One must be careful with the latest promotional item which has been re-released, re-packaged, and re-marketed. Long term studies have not been undertaken. It is a lot like stem cells. We were told that the lame would walk and the ills of mankind would be yesterday's news.
Some laboratory studies in cancer cells and animals have suggested that pregnenolone may stimulate the growth of hormone-responsive cancers such as prostate and breast cancer. Again, no long term studies have taken place. Before trying something new, ask your doctor because the potential for drug interactions is real. Your body produces pregnenolone already which is then turned into the hormones your body needs. I think that caution is the key word.