What can cause a missed period?

If you miss your period altogether, the first thing to rule out is pregnancy. Once you have done that, another possible cause is anovulation, which simply means you did not ovulate that month. It's possible that your next period may be heavier or longer if you have skipped a period in between.

For most women, incidental anovulation is normal and not a cause for worry. Some women simply have a more-sensitive endocrine-feedback system so that changes in stress, weight, and other factors cause shifts in their menstrual cycles.