"Stevie will fly out first thing in the morning, so he'll miss three days, Tuesday, Wednesday and Thursday," said manager Buck Showalter, who expects the club to add another player during the time Clevenger goes on the paternity list.
"Stevie talked to me in detail about it and he needs to go. Hopefully this time tomorrow, we have a nice addition to the Clevenger family."
Originally, the plan had been to induce labor on Sept. 17, and then it was pushed to the 10th, but Showalter said there's some blood-pressure stuff and other things going on, and Tiffany went to the hospital on Monday.
As for who the O's -- who made four roster moves prior to Monday's game -- may bring up, Showalter said they have some things already in place.
"It depends on what we do with a lot of different things, the way the game goes tonight," he said. "We'll see what our needs are."
Brittany Ghiroli is a reporter for MLB.com. Read her blog, Britt's Bird Watch, follow her on Facebook and Twitter @britt_ghiroli, and listen to her podcast. This story was not subject to the approval of Major League Baseball or its clubs.