Investigators don't suspect criminal intent and that the woman's husband is cooperating, said Yakima County Sheriff's office chief civil deputy Robert Udell.
The 27-year-old woman is eight weeks pregnant. She was shot once early Friday morning in the couple's bedroom. She is in the hospital in critical but stable condition, Udell said in a statement.
The Yakima Herald-Republic reported that there no major updates Sunday.
The couple's names were not released. Udell said they were waiting to notify the woman's family to release her name. Her husband is in his 20s.
According to entries in the sheriff's online activity log, the woman's husband initially reported an intruder was in the residence and then stated he had accidentally shot his wife. That call came in before 6 a.m. Friday.
"Male saying, 'I can't believe I did this,'" a dispatcher reported.