I used a Baby Jogger with my little boy, from around nine months to three+, he loved it, it really allowed us to get out together and I even trained for a marathon with it. I got mine on Freecycle, would you believe, so didn't pay a penny, they do come up on Ebay but tend to hold their value because they are often not well used.
The best ones are the running specific ones, but they are pricey and not easy to use on public transport etc, they are so long! I got my BabyJogger on Freecycle, it's worth a try - I had two offers! It meant I was able to train for a marathon and still get out with my little one. The advice is that you shouldn't put the baby in such a buggy until they can support their own head, so usually around six months (we got ours at nine months and he loved it).
Good luck, enjoy your pregnancy and don't rush back too fast too soon.
(there is a fantastic pregnant runners support thread you should look up, I found it really helpful)