What do you say to that?
One thing if we were 25, but we're both 40.
Serious replies only please.
At that age, I would have some serious second, third and fourth thoughts about doing it. I am adopted, and my mom was 37 years old when they did this. My dad was, I think, 43. They had finally attained a position in life where they could both afford to have a child, and where Mom did not have to work as well. I was a difficult kid and... it wore on them.
My first thought would be "You know how tired you are after a really tough day at work and then doing errands, and then having a surprise thing sprung on you at the last second once you are home and so you only ever get any rest, maybe, when you finally get to bed an hour or two later than normal and know that'll make the
next day even worse? Imagine that happening every single day without a break for at least the next 10-15 years."
Another consideration to have is your health. Are you going to feel like running around for an entire day in DisneyWorld in 120-degree temperature when you're 51? Or getting involved with baseball or scouting or swimming lessons, or any number of other things? Only many years later did I realize why my parents didn't want to do a lot of things other kids parents did: they were old! They were tired! In many ways, it was like being raised by granparents. None of my friends parents were friends with mine, because many times they themselves could have been my parent's kids. There will also be one heck of a generation gap to consider, there. Your children will be like aliens to you by the time they are 20.
Also: are one of you much more likely to die and leave your partner to shoulder the entire burden? My dad died when I was 11. Do either of you want to be raising a kid by yourself when you're 50? (In fact, my parents were the youngest and also the longest-lived of any of their families, so by the time I was 11, I'd been to a score of funerals as all my relatives died off - by the time I was able to really interact with anyone on an adult level, there was only one left).
How is your support structure? Do either of your have close-by parents to take some of the burden? And if you do, well, they're in their 60's at the very least.
Now, people are having kids later these days. Longevity has gone up dramatically even since I was born. So this might not be such a concern for you as it was for me.