Justaperv Amazing could you please make a tutorial how you did those? Especially the doggy pose and last ones? I've been struggling to get a good giant belly in daz but it looks like a pancake whenever I try to put the figures in those positions.  The texture also seems to blur out whenever I use pregnant morphs. I'd love to know how you got the stretch marks, as well as having the outfit stay below the waist.

I have all the shape morph bundles.

I learned how to do these mostly by experimenting and teaching myself.  There are some good tutorials online, which did help me, but I learn better by doing it myself and seeing what works and what doesn't (and as you found out, a lot does not work!). 

The reason your bellies look like a pancake when you morph them is most likely because the pose you are using has the wrong settings for pelvis bend and abdomen bend angles, causing the belly to fold on top of itself.  In the pose pane, try pelvis bend 0 to +10, lower abdomen bend -10, upper abdomen bend -10, lower chest bend, and upper chest bend +15. 

The stretch marks and linea nigra are made by modifying the torso textures in photo editing software.  You can access, change, and load these from the surfaces pane.  This is also how I add writing on the bellies, like I did recently on Belle.

Fitting the outfit is the hardest thing of all.  What I do is use d-force to fit the clothing naturally.  You have to make an animation with the girl starting in a base pose and un-morphed state (flat belly).  Then go 60-90 frames forward on your animation pane and apply all your poses and morphs.  Load a piece of clothing (clothing has to be d-force compatible or have a d-force modifier applied to it) to your character, and then run a d-force simulation (set up to run the full animation timeline).  This will run an expansion animation/simulation and the clothing will stretch and/or slide down under the belly.  This method works well, but there are tons of settings and tricks you need to do to make it work.  Even with everything I've learned, only 20% or so of the clothing I have will fit bellies as big as these girls have.  Probably about as good as the odds of finding clothing to fit them in real life!

If you need more, check out this thread: https://preggophilia.com/daz-3d-guide-fo...-renders-t  I have a long post in there (post #8 on the first page) that explains more.

Thanks those are some useful tips. I'll just keep practicing I guess.

"This will run an expansion animation/simulation and the clothing will stretch and/or slide down under the belly"

I've been able to get that done with dresses, but I wish we could get the cloth stretched over the bellies rather than unrealistically shrivel underneath them.

Edit: Oh wow. Bending the back to those parameters worked. I also locked them for using poses, which I didn't know you could do in daz until now.