It looks as if she's been shot , in the trailer...
In the key art she appears with the baby and the gun, and in the trailer, just the gun...
I wonder if there'll be a choice to leave the baby so Clem can conserve her strength after getting shot?
Leave the baby= Clem doesn't have to exert herself much, as a result, she lives as she reaches the final place.
Take the baby = The weight of having to carry the baby in one arm and the gun in the other makes her strain her wound too much, and by the time she reaches the final place, she bleeds out. Baby lives instead of her.
If it's indeed a pistol gunshot, maybe Bonnie acted as some sort of meat shield for Clem? Clem is standing directly behind Bonnie, whom Maud, the only Russian with a pistol, is aiming at.
The shot would go through Bonnie and her backpack, and finally hit Clem, with much less force thanks to Bonnie. Maybe that's why it didn't do much damage?
I don't have a gif of that scene, but during it they're both stepping to the right, alligning perfectly with Clem, with Bonnie moving closer to Clem as things get heated up. Her shielding Clem would be a nice way for Bonnie to feel like she redeemed herself. She tells Clem she still feels guilty, after all...
Vitali seems to be aiming directly at Kenny
And Buricko is aiming at Mike and Luke:
Here's a rough map of their positions when the shootout starts , Maud, Clem and Bonnie are almost alligned: