Em, sorry I only have a bad story.. I am convinced that Vitex caused my mc's. I had a mc at 15weeks in aug 06 and started ttc again in feb 07 with no luck and started to take the vitex around July and it all went downhill from there. I had one confirmed mc and I dont know if the others were chemical pg's but had a couple of cycles with +ve hpts and triphasic charts and just ended up bleeding before the 5th week.
I stopped the vitex and gave up hope basically until one day I saw a sign for a chinese medicine man. I have had about 4 weeks of weekly acupuncture and chinese herbs and am so shocked to find out that I am pg and so far so good.
Best of luck with your decision. Just be wary of the vitex though, my naturopath told me that it is very powerful stuff. It also messed my cycles a bit just like kylie.