However, I find it interesting from a scientific standpoint. There are of course a myriad of reasons people can't get pregnant, and it is very common for those who can't get pregnant 'naturally' to be able to safely carry a child to term.
This is something I would struggle with if I were considering fertility treatments.
A dear friend of mine spent a small fortune getting preggers only to have it fail - twice. They saved for another 2 years and tried one last time. This time success, and twins! Then at 24 weeks she went in to labor and they couldn't stop it. I don't know what folks know about 24 week old babies, but lets just say that it has been a rough road. They are awesome parents, they have awesome kiddos, but I know, because she is my friend, that she has dealt with a lot of guilt. If nothing else, us moms are awesome at the guilt thing!
From a personal perspective, my kiddos were conceived naturally. I too ended up with twins, and one had a rare condition (absent end diastolic flow of the umbilical) and on top of that, one of the placentas grew on top of the other and I ended up with a partial placental abruption. Long story short, my guys were preemies too.
I asked for a tubal ligation when we were discussing the c-section, and my doctor (I think wisely) told me I was probably not in the right frame of mind to make that decision. That I was healthy and every single complication I had had was due to having twins and not due to anything with my body and its ability to support a pregnancy.
As the twins grew, people would ask me if we were going to have more, and honestly, while I would LOVE to have more kids, I just can't imagine putting an older sibling through what DH and I went through with the twins. I know the odds are minute of me having another difficult pregnancy, but it just felt... selfish? to have 2 perfect kiddos and go for more knowing what I know about the risks. Maybe I'm just a weenie, but the risk wasn't worth it to me. NOT that I begrudge anyone else's choices. As has already been said - my body, my choice.