Yes, it is nutritive and supportive and safe. Agree with Genesa's reply. Western medical doctors are woefully ignorant about herbs and other 'nontraditional' therapies, so they usually just give a blanket warning to simply stay away, in order to be 'safe'. It's too bad, because herbs like these can provide really important, helpful nutritive support during pregnancy.
I'm a medical writer now, and I've found VERY few doctors who are openminded enough to learn about therapies other than what they learned in med school. But herbs have been used far longer than western meds - and many western meds are derived directly from plant sources.
There are many sources of info about the use of herbs during pregnancy. Here is a quick summary/ intro I just found on quick search: http://www.childbirthsolutions.com/articles/pregnancy/her...
I have used herbs for many years, and used to work at the Herb Research Foundation in Boulder (no longer exists, unfortunately). I would recommend some books including:
Rosemary Gladstar's Herbal Healing for Women
and
Susun Weed's Wise Woman Herbal for the Childbearing Year. You may find this one a little 'out there' in terms of style, but she's got good info.
I have a reference book called the Natural Pharmacy, which is a good source that includes info about research that has been done on each herb or condition. There are many good herbal books though, if you want to check them out even at a library or peruse at a bookstore.
Take care, and enjoy this time! Best regards.