@obedientsacrifice I think you’re actually doing a great job of shutting this down on your own! If I had to advise you I’d recommend saying something quite similar to that. (Something else you could try is ‘pretend to not understand’: just asking genuinely confused what they mean by that. Usually that makes it stop pretty soon because nothing is more unfunny than explaining a joke. But I think it’s good to send a stronger message than that if you want to shut it down for the future as well.)
The thing is, you can’t shut these jokes down and keep up the good spirits at the same time. It sounds like this is a habit deeply ingrained in your family. For frame of reference, I’m no prude and I enjoy joking like this with my husband, but I find the examples you mentioned pretty appalling. I wouldn’t let this go either. But your family isn’t going to like that. That’s something you’re going to have to accept. They’re going to label you a prude, well let them. If you do this a couple more times they’ll probably get the message.
You could also try to address it separately in a phonecall, that you’ve noticed that they make sexual innuendos about a baby, and that you think it’s inappropriate to do that about a child. You’re never going to be okay with it and please don’t do it again. I probably wouldn’t bring your own experiences into it but that depends on your relationship with your family obviously.
The nuclear option is just to ask if they’re pedos but I wouldn’t necessarily recommend that
.
Good luck! You’re a good mom that you’re doing this.