Wentz and his girlfriend, Meagan Camper, welcomed their son. Saint Lazslo. on Wednesday, Aug. 20 in Los Angeles, according to People.
"Mom and baby are happy and healthy," Wentz's rep said. "They are thrilled at the addition to the family and Bronx is over the moon to be a big brother."
Wentz and Camper decided not to learn the sex of their baby while she was pregnant and they didn't find out it was a boy until he was born. Back in May, Wentz said, "We're waiting. I think we'll probably do a surprise on this one."
Saint is joining big brother, Bronx, who is now 5 years old — and the son of Wentz and his ex-wife, Ashlee Simpson.
Wentz made the pregnancy announcement back in February by posting an Instagram photo of his hand on Camper's stomach. He captioned it with, "We're super excited to announce we're expecting a baby."
Although Wentz and Camper are not yet married, they have been together for three years and said they talk about marriage all the time.
"I feel really lucky," Wentz recently said of his relationship. "It's really interesting when you're in a relationship with somebody who's truly my best friend. I talk to her about everything."
Although Wentz and Camper haven't solidified any wedding plans, they apparently had been planning a pregnancy for a while. Wentz seems over the moon to be a dad for the second time. He said, "What's more exciting than having the pitter-patter of another little gremlin running around?"
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