I don't really know much about the medical side of things, but I have two boys that are 15 months apart and I think it is great having them so close together. Our baby #2 was a surprise, but we were considering trying and I had checked with my midwife about having them so close together, she thought my body would be fine, and I can't say that I had any difficulties before, during or after either pregnancy. And my recovery after baby #2 was even faster than after the first baby (I had torn a bit with my first, but no tearing with the second and a pretty fast delivery probably helped). I felt great immediately after he was born. My mom had 7 children and the first 4 were born within a span of 4 1/2 years. She told me that was really hard on her body. But that is 4 pregnancies very close together. I don't think only 2 pregnancies would be so hard on you. I don't know if there are considerations with having another baby so soon if there were any complications with your first pregnancy/delivery - I would check with your doctor/midwife.
A few reasons why I am glad I had them so close together: While pregnant with #2, my first baby was still taking two naps a day, so I got to have a morning and afternoon nap myself (very helpful toward the end of pregnancy when I was sooo tired). When it came time to potty train my first child, the baby was old enough that he didn't need to be held/fed constantly and it freed me to help the older child (I know so many people who have their babies 2 years apart and I don't know how you potty train a 2 year old while caring for a newborn!). And my favorite reason for having them close together is that they are best friends. They are 3 1/2 and 2 now and they are each other's favorite person in the whole world. I know that can happen with children of any age difference, and having them close together does not guarantee that they will adore each other, but it sure worked out that way in our family and I love it.
The downsides of having them so close together: Toward the end of pregnancy with the second baby, my first baby still wanted to be held quite a bit and that is difficult to be carrying around a 23 lb. toddler while 9 months pregnant (but I would say the two nap times were worth it!:) You have two babies for a little while, and that is not easy, though I don't know if having a toddler and a baby is really any easier. But babies are labor-intensive so it can be exhausting having two at the same time. You have two in diapers for a while, which didn't bother me too much, but it does get very expensive.
I hope this helps you make your decision!