I had a friend whose one broodmare's belly almost touched the ground just before foaling. I made tge skateboard comment and we all laughed. I turned my back and that mare nipped me! We laughed even harder.
In the case I had the mare didn't abort, but was shocky after foaling. We were very fortunate that our foal was healthy and vigorous although maybe a bit premature. I would just suggest that you might want to discuss this with your vet ahead of time and do what you can to prepare.
The strange thing is, another breeder I know has had all 3 mares with this condition. The first 2 aborted (but mares survived) but they were able to treat and hold the third one off and got a live foal that needed some extra support after being born but is healthy now.
This morning Bug foaled a lovely (teeny) Colt we're calling "Bud" - From his hair coat, yes he's a bit preemie but WOW is he a strong little guy! Delivery was pretty textbook once she settled into pushing!
Bug wasn't sure about letting him nurse, so I gave him a supplemental bottle of banked colostrum just to give him a "reserve" of energy and such, and now they are both doing GREAT! *Whew*!