The couple had twin girls, Charlene and Myla, in 2009.
"I think after having twins we're somewhat prepared," Federer said after reaching the fourth round at Indian Wells. "I think we know what it's all about now, you know... how to set up the rooms, sleepless nights, kind of thing.
"So I think from that standpoint we're much more relaxed about the next baby.''
Though he would not reveal more details, Federer said the family was anticipating its newest member.
"For us it's exciting times right now," he added. "Myla and Charlene are happy to to welcome a little boy or girl so it's good fun right now. It's good times."
Date: 11th March 2014, Source: Tennis.com