Definitely state your case if he brings it up again.

Definitely talk to them about it, how your feel.
Delaying it will only worsen.
Surprised it took 3-months for that to be revealed, usually, 2nd or 3rd date I ask.

Oy vey. My style is to talk about stuff like this. Especially important stuff like this. HUGE difference in life choices here. My advice is to discuss it and make sure he knows your feelings.

As others have written, talk about it with him. Let him know how you feel. If the fact that you have no interest in having children ever is an issue for him, then it doesn't make sense to continue the relationship. If he says it isn't an issue for him, you'll have to gauge for yourself how honest he's being. I've had relationships with guys where we've discussed big issues early on (not the kids issue, but other things like drug use, alcoholism, whether he's married or not) and the guy has said one thing to me during the discussion, and I eventually discover the opposite is true. In some cases, I think the guy really wanted what he told me to be true, but he just didn't have the emotional strength to change it, so he fell back into his old ways. In other cases, the guy was just lying to me so he could have a temporary connection. It can be hard to gauge whether someone's telling you the truth or not about their particular issues and sometimes only time will tell, you'll end up angry with a messy break-up on your hands, and unfortunately that's just the way it goes. But that why it's important to talk about this issue with him now, to possibly prevent things from going that far, to hopefully get the truth from him now so you can figure out whether you should continue the relationship or not.

Have the discussion.
Immediately.

Sometimes men say things like that because they assume that all women get oooooeeey and awwwwwwwwey over crotchfruit.

It's your job to educate him as to your feelings about children/babies and the idea of having them.

Yeah, I think I would deffo say something. It will only get harder to deal with the longer you put it off.

If you're over 40 it shouldn't even being option. Perhaps he's just talking out of his ass. It's definitely time to set the record straight.

Talk about it. Get it out in the open. It's a must! You both have to be honest with each other.

He may not know that having a child when one is past 40 is very different for men as it is for women.

Top 3 reasons for divorce are related to sex, money and kid(s). You need to be on the same page with this and let him know you are 100% (or whatever percentage it is for you) not down to have a child. Good luck to you.