Amenorrhea or absent menstrual periods: When a woman does not get her period by age 16, or when she stops getting her period for at least 3 months and is not pregnant.

Oligomenorrhea or infrequent menstrual periods: Periods that occur more than 35 days apart.

Menorrhagia or Heavy Menstrual Periods: Also called excessive bleeding. Although anovulatory bleeding and menorrhagia are sometimes grouped together, they do not have the same cause and require different diagnostic testing.

Prolonged Menstrual Bleeding: Bleeding that exceeds 8 days in duration on a regular basis.

Dysmenorrhea: Painful periods that may include severe menstrual cramps.

Additional menstrual irregularities include:

Polymenorrhea: Frequent menstrual periods occurring less than 21 days apart.

Irregular menstrual periods with a cycle-to-cycle variation of more than 20 days.

Shortened menstrual bleeding of less than 2 days in duration.

Intermenstrual bleeding: Episodes of bleeding that occur between periods, also known as spotting.