...well I guess I'm going to go against the grain here and risk saying...
I think it's fine. There has been no proof that it harms the baby at all, in fact moms who smoked MJ had slightyl smarter babies for the first few years of the babies life. It is probubly better for you and the baby than taking medical medication.
I have a medical MJ card for my fibromyalgia and migraines. I stopped taking it a while ago just because I thought it was hindering my ability to conceive. But it was a lot safer for me and the potential baby than the other meds they could have put me on. Honestly, I think it has a bad rep. It's not a big deal. Will I do it? Probubly not. But I also didn't take any thing for my vomiting (HG) until I had already lost over 10% of my body weight from it last pregnancy. That was a mistake because my placenta was only 1/2 formed. I was lucky to have a healthy baby.
Anyways, I don't know if I"d do it in the first trimester. But I'm a fanatic about not taking things in the FT. However, I can't say if I get a really bad flair up of fibro, or a debilitating migraine in later months that I won't take one, or smoke some.
No one would judge me for getting a shot of whatever narcotic for a migraine that makes you blind and paralyzed. So no one should judge me for using a natural rememdy
ALL that said. I think MJ for anything other than medical purposes is not right, ESPECIALLY not in pregnancy. And you should have a medical MJ card to use it. Thats my 2 cents