Mary let out a squeaky purr as she pushed in her round belly, feeling the air inside her shift around. She let go and watched her rubber skin blimp back out into its pregnant-looking bulge. It felt incredible, to have nothing inside but light air. She jumped up, squealing with glee as she rose higher and higher, very slowly losing speed and reaching over fifty feet off the ground. As she slowly descended, she admired the broader view she had from the height, and once back on solid ground she stuck the air tube back into her mouth and twisted the nozzle.
As she watched her body inflate wider a bit more, she noticed her height surpassing nearby trees. She must be around twenty-five by now...maybe thirty. Her belly stopped looking merely pregnant; its pert shape expanded and overflowed around her entire waistline. Her eight breasts squeaked against each other as they slowly grew tighter together. Her tail puffed up twice as thick and her paws began to round out. She tried wiggling her toes, but didn't see them move very much.
When she reached the height she was at in the apex of her jump, she looked up from her own body to see the horizon. She could see hundreds of stores and houses. There were much more trees in this part of town than she had realized, as a majority of her view of buildings was obstructed by green foliage. Still, trees or not it looked like she was the tallest thing around now. She grew up to seventy feet, her body looking rather fat. She was still growing up faster than out, but she was clearly on her way to a good round form.