Such an interesting thread. Disclaimer, I have one DD, born when I was 39, after getting married at 22. Just a little gap there. There was a lot of ambivalence, times when I wanted and he didn't, times when he wanted and I didn't, then we looked at our lives and both wanted and went for it. And retroactively I was so thankful for birth control - without it I would have had 10 children, I get pregnant so easily (only 2 months trying at 38). There are advantages and disadvantages to having one (I knew we were allowed just one, long before MMM posted). There are advantages and disadvantages to have them late (I was at least 10 years older than the mothers of my DD's friends). And there are advantages and disadvantages to never having them.
There are times I look at people with 3 or more and see how much that choice has affected their lives, and the planet, and wonder about their choice. But it is their choice. Some of them have commented on my only - but it was my choice, and she is a capable, social, accomplished adult. And did we get comments all those Dink years.
So, bravo to knowing yourselves well enough that you have made the right choice for you!
Dinarik, I think women think about it more because we are the ones doing the pregnancy and the ones more socially expected to make more changes in our lives re childcare. Not to mention the ticking clock. Men mostly don't realize that their ages can also affect the baby.