If she really hasn't peed, once you hit the 24 hour mark, it's time to be concerned. However what's more likely is that the pee was absorbed into the diaper without your noticing, particularly if they are disposables. Has she been nursing? Is her fontanel sunken? Has she passed meconium? How is she behaving? These are questions your pediatrician will ask. I would call the pediatrician.
At home amongst the redwoods with my husband and my son, born 7/5/11, and #2 due in October 2015 Instant CNM, just add !