The club's public relations staff announced via Twitter that "all are doing well."
Jax is 6 pounds, 7 ounces. No word on whether he bats from both sides of the plate.
Roberts was placed on paternity leave last night, with pitcher Steve Johnson being activated from the disabled list and rejoining the Orioles at Camden Yards as an extra reliever.
Roberts is allowed to remain on leave through Sunday, but he could choose to return anytime this weekend.
Manager Buck Showalter suggested that the club would keep revisiting its roster options each day. He also said Roberts might decide, if mother and baby are resting comfortably, to head over to the ballpark and play.
We'll know more about the Roberts situation later today.