My 14 yr old daughter haven't had her period in one month? this happen before is it normal?

Its normal bec: It's normal because at this stage in the life of a young teenager, many at times they have anovulatory menstrual cycles interspersed with several months of no periods.

Not unusual: Cycles in the first year or so after menarche can be irregular.Many do not ovulate, which is part of normal cycle activity. Ovulation triggers the normal timing sequence.Many who have delay will have a heavier late period.A delay of 90 days or more is beyond the norm (2-6 wks common) and worthy of an evaluation.