The Olympian reports the prosecutor and defense lawyer for Rachel Bryan both agreed to recommend the 18-year term when she is sentenced Oct. 18 in Thurston County Superior Court.
According to court documents, Bryan allegedly admitted to police that she treated the boy roughly and shoved him onto his bed when he would not stop crying.
The baby's injuries were discovered when medics were called to Bryan's home near Centralia on Sept. 20, 2011.
Bryan initially told hospital workers that the boy was hurt when he fell off his bed. Hospital officials called police when they saw that the boy suffered a fractured skull and had lots of bruising.
When she was first interviewed by police Bryan insisted she had nothing to do with her child's injuries, but later broke down in tears and said she "made a horrible mistake," according to court documents.
Bryan allegedly told a detective that she "doesn't realize what she's doing" when she gets angry and often picked up and put her son down roughly.
She said that on Sept. 20 she could not get her son to be quiet and drove him down on the bed so hard that he bounced, the documents said.
"It wasn't very nice. It was rough," Bryan said, according to the documents. "I shouldn't have done it but it wasn't me. When I get mad my bi-polar comes out."