Can we still butt in even if we haven't had that exact same experience? :-) I recently gave my .02 on a similar topic (a member who had questions on working towards a PhD with a new baby), so now I feel inclined to answer your post as well.
I have mixed feelings on this. As I mentioned in that other post about pursuing a PhD with a newborn, I recently babysat my 3 month niece and I thought to myself how there would be just no way I could go to school with a very young baby (I am working on my master's degree with five children, but my kids are 9,6, 5, 5, and 4, which, as my newborn neice reminded me, is a completely different ballgame. They are all in school all day long, except for the youngest). It can be DONE, I'm sure, but I wouldn't think it would be someone's first choice. My gut reaction advice would be to wait until you finish your BA and then have another baby. That's just my gut reaction, not knowing any other information (your age, fertility issues, etc.) But if you are young, etc., I would wait. It's nice to have children close in age, but it isn't everyhing. And sometimes there is something to be said about having them farther apart--my life would be SO much easier if we had spaced our children farther apart. It can be really tiring and stressful, especially in the early years. I remember when my kids were little, things were insane with all the diaper changings, the mess, the toddler regressing slightly, etc. Again, I can't imagine going to school with a newborn--and a three-year old (or so). It just sounds so insane. And what if something does go wrong with the pregnancy where you have to be on bed-rest, etc (and it can happen)? Then will you have to start paying off your student loans immediately? And even though your husband can watch the children while you are in class, how will you have time to study, etc.? One child is difficult enough, but the newborn might be hard. We forget how hard it is to have a newborn--even my neice seemed hard, and she is much easier than any of my children were as young babies(four of my children were very high-need, screamer-type babies).
But then, the other argument is that you have already (I am assuming) gone to school with a newborn/baby? And now you are able to study with a two-year old--wow! :-) You probably know what you're getting into more that someone who has never had a child, so that's in your favor. And frankly, I think if you really want something, you should try to do it. Within reason. I mean, everyone really thinks I'm insane, too. But I do manage to juggle things.
I assume professors would be understanding about giving birth, etc., (and legally, they'd have to be).
I hope I don't sound negative. I just know how exciting it is to think of the possibility of a new baby, but it might be more difficult than it needs to be. I purposely waited to begin my master's degree until most of the kids were in school (I wanted to wait until my youngest started kindergarten, actually, but my DH said he'd help out and to go ahead and start earlier. So maybe I'm too cautious?) In the end, you just have to make the decision that is right for you. Good luck and let us know what you decide.
Hope I didn't blab too long!
Kim