Here's a <a href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=10754818" target="_blank">study</a> that was done on it I think it sums it up well. Check out the Red Raspberry Leaf Tea Tribe in the I'm Pregnant forum too, it's back a page or two.
I start drinking it around 12 weeks with each pregnancy. Loose tea is MUCH better than tea bags. I brew mine in a large sauce pan using a large tea ball for the loose tea, I also add a cinnamon stick for flavor.<br>
I drink 1 cup (6-8 ounces) per day for the first couple of months then move onto 2 per day and now at 36 weeks I am drinking 2-3 large glasses per day. I like mine cold since it is easier to drink that way. I actually drink an infusion of RRL, nettle and oak straw.<br>
I can tell you that in the pregnancies that I drank the tea in I had MUCH less bleeding at birth and afterwards and recovered much faster.<br><br>
This pregnancy I have gotten mine from <a href="http://www.gentlemoon.com" target="_blank">www.gentlemoon.com</a>. With the last two I got it at Whole Foods but they stopped carrying loose teas <img alt="" class="inlineimg" src="http://www.mothering.com/discussions/images/smilies/irked.gif" style="border:0px solid;" title="irked">:<br>
If you do a Google search you will get several hits but I have been very happy with gentlemoon and they also carry other stuff I needed for pregnancy/birth.<br><br>
<a href="http://www.mothering.com/discussions/showthread.php?t=347728" target="_blank">Here</a> is the link to the RRL Tea Tribe.<br><br>
I started drinking it in my late first trimester, and continued throughout the pregnancy, drinking it stronger and stronger as time went on. My spontaneous first labor was only 12 hours long, from first contraction to birth. <img alt="" class="inlineimg" src="http://www.mothering.com/discussions/images/smilies/smile.gif" style="border:0px solid;" title="smile"> I'm definitely doing it again next time.