The 41-year-old No Doubt singer had second son Zuma in 2008 and said that she felt too 'out of touch' to write any music before reuniting with the band for a tour.
She told Contact Music, 'I hadn't planned on doing a tour. I'd had Zuma, I felt so gross I got so big and felt so out of touch and not cool. I was trying to write this cool record and nothing came out.
'I felt so bad because you've got this whole band waiting, but I couldn't write. So we said, 'Let's go on tour'.
'We had no new single, we hadn't been on stage together for, like, five years, and every night I'd get teary-eyed because of those old songs.
'I'm up on stage and I'm singing songs about relationships I've had and I'm looking over and my kids are watching me. It's very surreal.'