The Black Eyed Peas star said she and her actor husband have been collaborating for penning songs for their three-month-old son, reported Contactmusic.
"We have our own little home-written songs. We harmonise and we sing together. We can be quite conrny. Our son loves our little ditties," she said.
Fergie, 38, who initially struggled to adapt to the unpredictable routines that come with raising an child, said now she has learnt to balance her life.
"I'm a scheduler, I'm a planner, so I just really have to live more spontaneously and just, kind of, when he's ready to learn and be fed and he's ready to react and respond to me - he's first priority - and my emails will have to wait," she added.