I was doing some searches on David's Mother and his birthday. Although there aren't many things in Bible that can tells about David's mother or bithday, I found an interesting text from talmude sources.
As I understood, according to this text, Nitzevet, David's mother was separeted from her husband and changed with his maidservant at night so that she could have sex with him.
I just to confirm whether David's mother was separated from his husband.
this is the link