Pete Wentz  and girlfriend Meagan Camper welcomed their son, Saint Lazslo, into the world on Wednesday, People reports . According to the couple's rep, "Mom and baby are happy and healthy. They are thrilled at the addition to the family." It's the first child for Meagan, while Pete is already a dad to son Bronx — now 5 years old — from his previous marriage to Ashlee Simpson . According to the source, "Bronx is over the moon to be a big brother." Congratulations to the couple!