I'm not a doctor, but I am a mother of a child with a golf ball size hematoma and have learned A WHOLE LOT about them. A hematoma is just a ball of vessels, essentially tangled, but harmless. My son had one on the back of his neck since he was 3 months old. As he grew, it shrunk.... he's 12 now and it is gone. His was under the skin where my daughter had one external, it looked like a birth mark. The doctor explained that over time the vessels will slowly un tangle and the blood re-absorb. Of yours is simy on your stomach, you should have No issues. It will not effect your uterus or the fertility process.