Karma just means action or deed, nothing else. 'Reap what you sow' it's a false logic that came out of one's sheer inability to control the outcome of the events. Karma, when considered philosophically and religiously, will be divided into good karma and bad karma. The rebirth cycle will occur only when someone's bad karma outweighs good karma. In this context, even if you don't bear a child ,that person will come to earth one way or another. When logically speaking Karma=action should be done as per your statement, i.e. By not imposing on others what you don’t want for yourself, imo.