I am glad to hear that there are some moms here who can wade through the propoganda and talk some sense. Although I do not smoke, pregnant or not (but heck, I didn't even have caffeine or soft cheeses because I am a paranoid freak about that kind of stuff), in my past life as a serious student at UCB I did much research about this topic. (Yes, I do have references, but they are buried in my messy out of control garage and unless pressed I really don't want to go get them.)
First of all, regarding studies that people cite. Who do you think is funding these studies? Please know that the vast majority of these studies are funded by the US government in support of the war on drugs (which is a sham, BTW, but that is for another thread). Other establishments don't usually have the clout to get the results of their studies published - the results that show absolutely no effect whatsoever on babies whose moms smoked while pregnant or nursing. Alcohol, caffeine, and OTC medications, on the other hand, are potentially very harmful.
Regarding having your baby taken away, this again is propoganda. I mean, yes, my baby could be taken away or I could be arrested just if I'm in the wrong place at the wrong time - crazy stuff happens. But this has nothing to do with marijuana. Marijuana laws vary from state to state. In the state that I live in, posession of less than 1 ounce of marijuana (which is quite a bit IMO), is a misdemeanor, not a felony. You won't even be arrested - you will be cited. There is no law regarding ingesting marijuana while nursing or pregnant, just as there is no law against drinking or smoking cigarettes while pregnant. Pregnant women seek drug treatment all the time, usually for very hard drugs, and very few have their children removed. If their children are removed, it's because they were unable to provide any care for them, not because they smoked a joint. Heck, not even because they shot heroin.
Please make responsible decisions, and please please please don't believe everything you read. Question the sources, question their motives, follow the money trail, and then sit back and think about what makes sense to you. Does it really make sense that a natural herb would be more dangerous than alcohol, pills, cigarettes, genetically modified foods, or pollution?