Early pregnancy tests work by binding the hCG hormone, from either blood or urine, to an antibody and an indicator. The antibody will only bind to hCG; other hormones will not give a positive test result. The usual indicator is a pigment molecule, present in a line across a home pregnancy urine test.
Gas and bloating is a sign that food is not being digested correctly by the body. An inadequate intake of water will cause excessive stomach bloating. Water benefits the body by aiding with digestion because it supports a majority of the body's daily functions.
1 Stomach cancer - Stomach cancer is more common in parts of the world outside of the United States, but can be an important cause of abdominal bloating.  Colon cancer - Colon cancer can also have symptoms of bloating as an initial symptom, especially when it causes a bowel obstruction.