There is an article in the June/July Cannabis Culture called Cannababies that you really should read. I dom't have time to go look it up right now but apparently in moderation it is ok, though midwives recommend using a vap. because smoke deprives the baby (and you) of oxygen. There is also something about smoking the last month of your pregnancy, I can't remember if they said it caused you to go into labor, or it stopped your labor, but you should check that out before month 9.
Good Luck, and congratulations!