Zoo spokeswoman Sondra Katzen said the unnamed calf was born at 11 a.m. Friday to 26-year-old mother Allie in the Seven Seas dolphin exhibit, the Chicago Tribune reported Wednesday.
The zoo said no dolphin shows will be held for a time and the Seven Seas underwater viewing area is being closed to the public to give Allie and her calf time to bond and adjust to a nursing pattern.
Zookeepers said they also want to make sure the other dolphins get well acquainted with the new arrival before the exhibit reopens and the dolphin shows resume.
The zoo said the baby is "healthy and strong" and was born at 40 pounds and measuring 3 feet long.
Allie has previously raised two other calves, the zoo said. Tapeko, a 31-year-old dolphin sharing an enclosure with Allie, is expected to give birth this fall.