What are the causes for a missed period?

Anovulation: If you missed a period and your pregnancy test came back negative, then you most likely had an anovulatory cycle, meaning your ovaries didn't release an egg. This happens from time to time but if consistent, see your doctor because you may have a hormonal imbalance. Consider a birth control consultation to regulate your periods and avoid unplanned pregnancy.

Possible reasons: Reasons for missed /late periods: low body weight, obesity, marked weight gain or loss, over-exercise such as in endurance athletes, breast-feeding, stress, illness, eating disorders (bulimia or anorexia), travel, hormone irregularities, drug use, medications (i.e., birth control) or med problem(polycystic ovary syndrome or Asherman’s syndrome. #1 reason for missed period is pregnancy.