My daughter had her 1st periods last month she is 12yrs of age, this month she is late. is there a possible explanation except for her maybe being pregnant?

This is normal: This is not at all unusual. It takes some time to establish a regular menstrual cycle so she is actually not "late." Obviously if she has been sexually active then pregnancy is possible and it is simple to do a home pregnancy test, but hopefully she is not yet sexually active and her cycle not yet being regular is entirely normal.