I did not have serious complications with either of my pregnancies, but I DID have debilitating nausea with both. We debated and discussed when to go for #2, after the first one. I was so stressed about how I would deal, since our first was a little boy who was a real handful. Walking at 10 1/2 months, climbing, exploring and basically needing total attention during all waking hours so that he didn't "escape" and the house didn't get burnt down, lol. Grocery shopping was a completely stressful experience. I just didn't know how I would handle any of it pregnant (or even after with a newborn).
Well, my 2nd pregnancy, the nausea was even worse than the first. BUT, it was amazing how well things went, for the most part. My husband told me from the beginning something very wise: The older child may be 2 right now. But as you go through pregnancy, he is growing up also. He won't always stay quite the handful that he might be right now.
By the time our daughter was born (son was not quite 3 yrs at that point), our son had become amazingly "manageable". :) And helpful even.
Obviously, you want to have to least stress possible and a health pregnancy all around. But if your concern is how you will manage with a 2 yr old underfoot during any periods of bedrest.... keep in mind that your 2 yr old won't still be a 2 yr old for the next 10 months. They will be maturing also, and there are any number of ways that you can entertain them even on bedrest. Do you have family in the vicinity that might be able to help out during times of extreme need? Or close friends from church?
There was one point early in the 2nd trimester during the worst of the nausea (before I discovered zofran) that my hubby drove our son to stay with his grandparents for about a week. (They lived 3 1/2 hrs away, so they each drove halfway and met somewhere in the middle). It wasn't ideal, but it worked out. My mom came and stayed with us for a week and a half at one point also. The rest of the time, we managed on our own. Hubby was very accommodating and sweet. Again, I realize that what I experienced is not the same thing you had with your first, but the idea of letting family take your older child for a little here or there is something to consider. It might not be ideal, but it is worth considering as a viable option should there be complications this go-around. None of us are worse for wear because of it. In fact, my son has fond memories of those days with his Granddaddy, who is no longer with us.