I had heartburn and pretty bad acid reflux issues with both of my pregnancies (first one normal, HELLP @ 37 wks with second) and the location of the pain was similar to heartburn but it DEFINITELY feels different. It was not a burning pain but more of a pressure, almost like I couldn't catch my breath. It was right in the center of my chest, right under the sternum. It couldn't be ignored and no position relieved it. I am grateful I had the pain because I had no other significant symptoms (one isolated high BP reading one week prior that I think my Dr thought was a fluke). Because my BP was only borderline when I saw the OB and I had no protein in my urine, I was sent home. The pain continued to get worse and I went to maternity triage where they finally did blood work and caught it. I would suggest requesting a blood test if you suspect it may be HELLP. I think I was not diagnosed immediately because I did not have PE or any related conditions with my first pregnancy. From my understanding, the blood test is the only way to know for sure.