Pete Wentz is now a father of two!

The 35-year-old bassist, backing vocalist, and primary lyricist for the rock band Fall Out Boy, and girlfriend Meagan Camper welcomed their first child together.

Camper, 25, gave birth to a baby boy Wednesday, Aug. 20, in Los Angeles. They named the new addition to their family Saint Lazslo.

"Mom and baby are happy and healthy," a representative for the rocker told People. "They are thrilled at the addition to the family."

"Bronx is over the moon to be a big brother," added the rep, referring to Wentz's 5 ½-year-old son with former wife Ashlee Simpson.

Up until the baby's birth, Wentz didn't know the sex of his second child.

"We're waiting," Wentz told People in May. "I think we'll probably do a surprise on this one."

The musician revealed his model girlfriend of three years was expecting with a lovely Instagram post back in Feburary. "We're super excited to announce we're expecting a baby," he wrote on the image-sharing site along with a photograph of them snuggling in bed.

The couple, who celebrated with a stylish baby shower in May, has always wanted to start their own family. "They've been planning this for awhile," a source close to the couple told the celebrity magazine back in February.

"What's more exciting than having the pitter-patter of another little gremlin running around?" Wentz told E! News in May while speaking about his growing family. "Now it will be two-on-two."

Wentz got engaged to Simpson in April 2008. A month later the two tied the knot at Simpson's parents' residence in Encino, California, where her father officiated the ceremony. In February 2011, Simpson filed for divorce, citing "irreconcilable differences." She asked for joint custody and primary physical custody of their son, Bronx, along with spousal support.

Wentz and Simpson were married for three years, according to Us Weekly.