When a parent should worry that their daughter may be is late, because she's never had a period before would be at age 16. If she's already shown signs of breast development. If she has no breast development whatsoever and she's 14, that's too late. So at that point either 16 with signs of breast development or 14 with no signs of breast development she should then bring her daughter in for a medical evaluation to get a hormonal work up and may be some other tests on to find out why she has not started having her period. So she is late in starting her period. There are several different medical conditions that could be responsible for that. Of which the most common would be the Thyroid condition, but there are some other not as common conditions that could exist. Such as an anatomic defect of the genitals, it could be a hormonal imbalance or hormone defect, hormone Instamatic defect. So it really would take a medical professional to sort through the different possibilities and run the appropriate medical tests to determine what is the cause of your daughter's late menses. Another condition that could also be responsible is Polycystic Ovary Syndrome, which is not common but we are seeing more often among young women. Other conditions that need to be considered as well would be Anorexia or Neuroses or if she's a high performance athlete, or what we call the female athlete triad, because she's a long distance runner, marathon runner, competitive gymnast where she has really low body fats.