The 37-year-old star, who shot to fame in the group in the 1990s, would love to have a sister for her two sons, Beau, six, and two-year-old Tate, reported Contactmusic.
Bunton, who is engaged to Jade Jones, said, "I wouldn't mind a son or a daughter, if I had another boy it would be amazing, or a girl, I really don't mind. I do have a lot of Spice Girls outfits I could hand down though if I had a daughter.
"I've also got a niece though so if it doesn't happen then they will still be going somewhere special," she said.
"Beau loves music, he really loves music... If he did want to be a singer then I would support him in that and whatever he wanted to do," Bunton added.