Nathan will be the first band member to double up on kids.
The singles "Sex on Fire", "Use Somebody", and "Notion" all peaked at number one on the Hot Modern Rock Tracks chart.
The album was their first Platinum-selling album in the United States, and was also the best-selling album of 2008 in Australia, being certified platinum nine times.
The band's fifth album, Come Around Sundown, was released on October 18, 2010.
Their sixth album, Mechanical Bull, was released on September 24, 2013.
Among those celebrating were Caleb's bandmates and Adridge's fellow Victoria's Secret babes, including Alessandra Ambrosio.