General aviation pilot reported a near miss with a helicopter during climb from a non-towered airport. Pilot took evasive action to avoid a collision.

Narrative

I held short of Runway 19 at SGU at B1 until all incoming traffic had arrived and the runway was clear of all traffic. I gave proper radio calls on frequency as to my taking Runway 19 for departure. No return radio calls came back with conflicts. I entered the runway lined up for departure and proceeded to takeoff. As soon as I reached an altitude of 200 feet directly in front of my aircraft was a helicopter at the same altitude about 100 feet directly in front of my aircraft traveling from east to west across the runway. I had estimated 1 to 2 seconds to collision with the runway incursion this helicopter had created. I pulled power and pushed the aircraft down toward the runway quickly and flow under the helicopter. The helicopter was traveling from east to west traveling over the runway at the same time I had Runway 19 for departure. The pilot of the departing helicopter had not given radio calls to his intentions. I was able to gain control of my aircraft without contact with the runway or any other object so continued on the planned flight. I radioed the pilot of the helicopter and he told me he never saw me taking off and I don't believe he saw anything that took place. When leaving the area I took note of the offenders tail number on my aircraft ADS-B and found it to be Aircraft Y. If I had not taken evasive action we would have [to] close SGU to clean up the debris and our bodies at St George airport SGU.