Fergie's "obsession" with the gym is halting any baby plans.
The 'Glamourous' hitmaker has reportedly shelved any plans for her and husband Josh Duhamel to give 21-month-old Axl a little sister or brother for now.
A source told US' OK! magazine: "Another baby just doesn't fit in with Fergie's life at the moment [even though Josh is] desperate to have another kid."
The 'Safe Haven' star has made no secret of the fact he wishes to have another child with the 40-year-old singer.
He said previously: "We've got to be very strategic in our planning for it. But the plan was to always have at least two.
"It's still crazy to think that kid is mine and that we made him. It's like, 'Holy (expletive)! We made him!'"
And the 42-year-old actor is particularly keen on having another son after growing up with three sisters taught him girls could be tricky as teenagers.
He said: "[My sisters] taught me that I would be really happy to have another son.
"Girls are great. I would be totally happy to have a girl, but ... they get to be those teenage years and [want] independence, you know? It isn't always easy - especially for the mother."