It would be an insane amount of work to do pregnancy for all the girls, but one girl getting pregnant during her story wouldn't be nearly so much. It would just require her repeatable scenes and her appearances in other girl's storys to have pregnant versions. It would still be a fair bit of work, but nothing like doing it for all the girls. (or doing it independently of story, which would require multiple versions of all story scenes too). If anyone would get that treatment, I'd expect it to be Ashley. Given her proclivities, it might make more sense for pregnancy to be a part of her story rather than tacked on at the end.
Even then it would be some amount of time he need. If the pregnancy thing is more than "insemination", wait, "givin birth" and be done, than he need at least one scene per girl for all actions, at least is it unconditional to story or date. If he would make the pregnancy more realistic, so that the char would gain their belly gradually he would have even more work.
Additional at the moment they are 8 girls, thus for simple pregnant/no pregnant without that gradually approch:
256 different possibilty combination for all 8 girls together. Even if only 2 girls are in a scene it is 4 times the work.
If he does a approch with 3 stage: 3 times woirk for a scene with 1 girl, 9 times for 2 girls scene, 27 times for 3 girls scene, ..., 6561 times for an all 8 girls scene.
And if you only care about the pregnancy in her story scene and not on all scene, then it looks funny for me. Story scene girl pregnant (>=7 month), next scene shower scene, girl slime as always. If this would be the solution
I rather wouldn't have pregnancy at all.