The Spice Girls are under pressure to increase their world tour to 50 dates, after an unprecedented demand for tickets from fans.
The band - Victoria Beckham, Mel B, Emma Bunton, Mel C and Geri Halliwell - are to hold talks with manager Simon Fuller to extend the tour after two million fans registered on the group's website.
However, the group - who have agreed to 11 dates and are already considering a further 14 shows - are said to be reluctant because of family commitments.
A source said: "The girls really want to do a huge tour but they're worried about how much they'll be able to commit to it because of their families."
Victoria - who has just moved to Los Angeles with husband David - has three sons, Brooklyn, Romeo and Cruz, and Mel B has two daughters, Phoenix Chi and Angel Iris.
Geri is mother to one-year-old Bluebell Madonna, Emma is due to give birth next month, while Mel C has just got engaged and has solo commitments.