The 38-year-old pop star performed on stage as part of the chart-topping girl group in 2019, shortly after giving birth to her third child - a son called Ford - in October, and Kimberly has admitted it's been an enormous challenge for her.
Asked about the pressure of being a Pussycat Doll, the singer told news.com.au: "It's more a pressure on myself to find acceptance within my skin and in my new body.
"The tough thing was I didn't have much time after a caesarean to whip it back into shape. It gave me the challenge of a lifetime, and a chance to accept myself in that moment for what it was.
"I stood in that moment as a woman and a mother doing what I love."
Meanwhile, Kimberly's bandmate Nicole Scherzinger recently claimed The Pussycat Dolls have "evolved" over the last decade.
Nicole, 41 - who stars in the group alongside Ashley Roberts, Carmit Bachar, Kimberly and Jessica Sutta - said: "Even our mindset is a lot different.
"We're always talking about empowering others, but it's really great to actually evolve into the women that we are and to be able to empower others out there."
Nicole also believes the group can have an empowering influence on their fans.
She explained: "We've each individually stepped into our own power. We can empower each other and that means we can empower our fans more."