Unfortunately, the full thing in all her pear-shaped beauty won't fit here, so I'll have to link to her elsewhere:
https://twibooru.org/3588517
https://ponybooru.org/images/3870078
https://ponerpics.org/images/7313021
The sketches are in Pregchan, of course.
Here's a new story, with new artwork by Jotun22, and for the first time with this anthology the artwork preceded the story:
https://www.fimfiction.net/story/526921/24/short-stories-with-pregnant-ponies/a-mundane-victory
Rarity smiled, putting the finishing touches on her new dress. Preparing for foals was busy—so many little clothes to sew—which had delayed the outfit for weeks. She’d be the talk of tonight’s party wearing it.
Rarity stepped into the dress, pulling it around her hindquarters magically. She noticed one problem: It didn’t seem to fit. She tugged until it threatened to rip, and changed her strategy. Rarity found the dress no easier to wear lying on her side or wiggling on her back, however, and huffed.
She’d taken her measurements perfectly, and chewed her lip wondering what was wrong.
“Oh! I took my measurements for this dress weeks ago.” She frowned. “I may have grown *just a little* since then.”
Magic dragged off and dropped the outfit. She had a beautiful maternity dress perfectly sized, for an earlier pregnancy. “Well, I’ll just have to wear this *next time*, I suppose.”