I drink a ton of it - 2+ cups a day, starting around 28 weeks. If I have this baby on time or anything close to it, I am definitely giving the tea credit.
It's probably a placebo effect, but my doctor agrees it can't hurt anything.
Edit: hit post too soon. I bought a 6-pack of boxes off Amazon for less than $20 IIRC. Yogi brand. I make it a cup at a time and put one pack of splenda in each cup. Honey or sugar is good too but I don't keep those on my desk at work.