Sorry about the typo, I meant to type "sternum."
The Heimlich Maneuver presses on the strenum, not the stomach, and a sternum is evident even on a very pregnant woman. Besides, the Heimlich is used when someone is choking to death. If you don't perform it, two lives are lost.
This is like a question they asked in our test in CPR class about whether you would perform the CPR on someone with fresh scars from obvious very recent chest surgery. The answer is yes, or they will die otherwise, whether or not you disrupt the results of a recent surgery.
Same method just underneath the breasts. It's the same as if an overweight man with a beer belly was choking. but our excuse is soo much better and cuter! :)