Matt Damon and his wife, Luciana, have welcomed a baby girl named Isabella, PEOPLE has learned exclusively. "The baby is here. Isabella arrived yesterday," Damon's brother Kyle told PEOPLE on Monday. "Mother and Isabella are doing fine," Damon's rep Jennifer Allen, confirmed to PEOPLE. "The family is very happy and everyone's healthy." This is the first child for the couple. Luciana also has a daughter, Alexia, from a previous marriage. "He's a terrific uncle and he's going to be a wonderful father," Kyle said of his brother, Matt. "Thankfully, Lucy has some experience, so that will help. Alexia is a terrific girl. They're all really close, they'll be an intimate family." [People]