The 36-year-old star has admitted that a distance has developed between herself and the duo, even though she's now closer than ever to Cheryl and has also maintained a good relationship with Nicola Roberts.
Kimberley - who has sons Bobby, three, and Cole, 14 months, with her husband Justin Scott - explained to The Sun Online: ''I'm closest to Nicola and Cheryl now and I do see a lot more of them.
''I do still speak to the others, but a bit more like you just check in with people that you work with, I guess.
''It's a different chapter in our lives now. We've got kids and things move on don't they?''
Although Kimberley has drifted apart from Sarah and Nadine, she's still got an incredibly close bond with Cheryl.
And she's revealed that her sons and Cheryl's 11-month-old son Bear - who she has with Liam Payne - enjoy playdates together.
Kimberley said: ''My sons Cole and Bobby get on well with Cheryl's baby Bear; they have a lovely time.''
Meanwhile, Kimberley recently admitted she is open to a Girls Aloud reunion.
The British beauty revealed that the girls ''may'' reunite to mark the 20th anniversary of their formation, which will arrive in 2022.
Asked about the possibility, she said: ''I wouldn't rule it out, absolutely not.
''It may be something that will happen in the future - maybe for the 20th. If the planets collided and it was the right time, then definitely.''
Despite this, Nadine recently suggested that Sarah is the only member of the band she's remained in contact with since their split.
She said: ''Sarah and I ... I don't see her all the time. I haven't seen her in a long time. But she knows she can phone me.''
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