The Maroon 5 frontman, who is set to marry his Namibian-born girlfriend in Mexico next month, is desperate to start a family with her as soon as possible, reported OK magazine.
"Adam and Behati want to have a baby right away, and can't wait to start trying," a source said.
The couple, who first started dating in May 2012 but briefly split last year before reuniting and announcing their engagement, are expected to exchange vows in an intimate ceremony at the Hotel El Ganzo in San Jose del Cabo on July 19 before jetting to South Africa for their honeymoon.