Four; all David's children by her, as the text positively affirms; and therefore Solomon is called her only son, Proverbs 4:3, because she loved him as if he had been so. Ammiel, called also Eliam, 2 Samuel 11:3. See Poole on "2 Samuel 11:3".
Related Commentaries of 1 Chronicles 3:5
1 Chronicles 3:5
5 And these were born unto him in Jerusalem; Shimea,b and Shobab, and Nathan, and Solomon, four, of Bathshua the daughter of Ammiel: