The short answer is that there are morphs available that could simulate a certain level of pregnancy.
This is an example :
This is a set of two morphs for creating pregnant models, one full-body and one genital. The full-body morph covers the belly and breasts, and can be used at different levels to get pretty realistic trimesters. (Shoutout to Yameteouji for the...
hub.virtamate.com
As for phase of crowning, that's a whole different thing and I can't say I have seen morphs that allows that much deformations.
Not that it's impossible to make, but more that the level of deformation might exceed the level of details you can get out of the mesh around the vaginal area.
It would requires a whole different level of modeling for the vaginal area with its own morphs (as morphs are either vertex or maps dependents meaning that the UVs and/or the position and number of vertex has to be more or less made for it).
Currently, 90% of the vaginal area is just a visual simulation created by materials & textures. If you remove those 2 elements, the vaginal would look like a gray-ish piece of flat Play-Do art. When you morph those faces as big as required for the crowning during birth, you will end up with some kind of visible angle around the crowning. (Imagine if, currently, the vaginal area is barely able to fit around a shaft-like form of a dick... how it would far if you attempted to fit it to a volume-variant level that is a baby's head or neck or body.)
I'm not judging your taste, but I got to point out that this kind of passion is rater a rare occurrence, hence there are really little chances that someone with the same kind of tastes as you would end up modeling and test such a concept in VaM out of sheer pleasure for it. You might have to look up for some artists that are up for the task at a cost. The least amount of people which like something, the lesser the chance you'll find someone working on it.
As for the water breaking, that's mostly on the animation, effect and timing side. (Manipulating morphs over time and starting and stopping effects at key moments. Enabling and disabling stuff along the way.)
Lastly, while you haven't covered it in your demand, I would guess that there should be a baby involved.
That, again, is a whole different matter and even more... a risky one because of the laws in various countries regarding the matter.
Long story short, involving an infant (0 to 13) in some war scenarios and making them get hurt is not well viewed and sometime illegal, but depending on the context it can be accepted as a relative side of war. When it come to a software that is as much used for sex simulation as VaM, that's a whole different degree of "acceptability" in the legal sense. While a project might start as something natural and kinda right, exposing the files to the public could result in it being used for other stuff and, yes, in certain countries the original artist that exposed the file is partially responsible if traceability is involved.
This is also the reason why, even in filmed porn, pregnancy-related sex are mostly limited to the first 3 or 4 months of pregnancy as, in many countries, the pregnant mother who act in the sex could get sued for displaying certain things done to her not-yet-born child. She could even loose right to raise her child even before it's born and if the child is born with any issues, she could get criminally implied as the cause of it.
I don't want to scare you, but just make you aware that pregnancy-related content is real field of mines in entertainment as to why you might not find a lot of stuff covering what you're looking for.
This is also why you're mostly only find porn stuff about forced birth out of movies or hentai movies usually have the budget to simulate it (or a slaving effect artist) and hentai are just drawn and no real person is involved in the act.
In case any 3D artists would like to get into this, I would suggest to not model a full baby head, but maybe only the top of the head (or just use a sphere) and limit the whole thing to up to the early stage of the crowning.
