Pat Neshek's first son, Gehrig, passed away on Wednesday just 23 hours after he was born.
"Please pray for my family. Tonight my wife & I lost our first & only son 23 hours after he was born with no explanation," Neshek said on his Twitter account.
Neshek left the A's on Tuesday to be with his wife, Stephanee, who went into labor.
He wasn't with the team as they celebrated their AL West title on Wednesday.
"Our hearts go out to Pat and Stephanee and we share in their sorrow of losing their young son. The entire A's organization will keep the Neshek family in our prayers and thoughts, as they try to come to grips with this tragic occurrence in their lives," the Athletics said in a press release.
Neshek went 2-1 with a 1.37 ERA over 19 2/3 innings this season.