Vitex is another name for Chaste Berry. Now, if you're trying to get pregnant, I doubt you are "chaste"! That name comes from its former use in monks to diminish libido. I don't know if it worked. I think a better, more descriptive name would be "LH booster."
Because that's what it does. It increases LH and decreases prolactin levels. In the U.S., studies of the effects of herbs are not conducted by pharmaceutical companies because herbs are unpatentable, but that fact doesn't stop researchers in Europe. In several studies with vitex, it helped to relieve premenstrual symptoms (PMS). By decreasing prolactin levels, breast tenderness was decreased, and the increase in LH boosted progesterone.
And that boost in progesterone may be helpful for conception. For women who have low progesterone, that would affect the second half of their cycle when the uterus is preparing to receive a fertilized embryo. Without adequate progesterone, the lining of the uterus isn't prepared properly, and a fertilized embryo may not find a good home in which to settle and grow.
How do you know if you have low progesterone? And how low is too low? Well, you should know that doctors disagree on how much progesterone you need to lead to successful implantation and pregnancy. However, we know that you need it, and more wouldn't be harmful. Thus, if chaste berry can help increase your progesterone, that would be good for those of you who may have a progesterone deficiency.
Back to the question of how do you know if you have low progesterone? The best way, besides a blood test, is to track your basal body temperature (BBT). It should rise after ovulation, and ideally, it should rise at least a half a degree to a full degree and stay elevated for at least 12 days.
I can't find any downside to chaste berry. It might not be the magic bullet, but if you have PMS symptoms, you may have excess prolactin and deficient progesterone. It could be worth a try for you. That, along with healthy chances in your lifestyle, and you may be picking out baby names before long!