Teenage Menstrual Cycle and Complications

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Whether you are a mom reminiscing about the days when puberty first hit or a dad who doesn't know what hit him, there are a few basics every parent needs to know about a teen's menstrual cycle. Menstruation is known by many names: "menses," "your period," "that time of the month," even "Aunt Flo." During menstruation, the uterine lining that has built up throughout the month sheds. This shedding of the blood and tissue from the uterus through the vagina is menstruation.

Menstruation is just one part of a woman's menstrual cycle. The menstrual cycle is a series of hormonal and physical changes that prepare a woman's body for pregnancy. If pregnancy doesn't happen, the body resets itself to prepare for another attempt at becoming pregnant.

Too Early, Too Late or Just Right?

Timing is everything to parents. Did she get her period too early? It is a problem that she hasn't gotten it yet?

In the United States, the average age of initial menstruation is 12 years old, but a girl can get her period anytime from the ages of 8 to up to 15 or 16 years old.

What Is a "Normal" Cycle?

A menstrual cycle is measured from the beginning of one menstrual period to the beginning of the next. The average menstrual cycle is about 28 days, but it can range between 21 to 45 days and still be considered a normal cycle. Menstrual bleeding typically lasts 3 to 5 days, although a range of 2 to 7 days can be the norm for some women.

During the first few years after the first period, your teen's cycles may not be regular or predictable. These early cycles are frequently anovulatory, meaning no ovulation occurs during the cycle.

Although cycles usually become regular within 2 years of the first period (menarche), it can sometimes take 6 years after the first period to ovulate regularly.

It would be impossible to predict which cycles would have ovulation or not, so it doesn't mean teen girls in these early years are not fertile.

4 Phases of the Menstrual Cycle

The uterine lining, the ovum (egg) and hormone levels are all changing and cycling throughout the entire monthly process. There are essentially four phases of the menstrual cycle: menstruation, the follicular phase, ovulation, and the luteal phase.

  1. Menstruation. The uterine lining and bloodshed, signaling the beginning of the menstrual cycle. This phase varies in length from woman to woman, contributing to the differences in menstrual cycle length.
  2. Follicular phase. During this time, the ovaries are being stimulated to produce a mature egg, and so they mature throughout this phase. Additionally, the uterine lining is growing, preparing for possible egg implantation if pregnancy should occur. The length of this phase also varies.
  3. Ovulation. The ovaries, by way of an ovarian follicle, release a mature egg after a surge of hormones that triggers the event.
  4. Luteal phase. This phase lasts a consistent length of time: an average of 14 days with a day or two variations. During this time, the uterine lining continues to grow, preparing for embryo implantation. The ovarian follicle becomes the “corpus luteum” - the yellow body that produces hormones that would help to promote a pregnancy if it occurs. If pregnancy doesn't occur, the cycle begins again with menstruation.

When to Worry

Menstrual irregularities sometimes indicate a medical condition. There are a few instances in which your daughter should seek a doctor's opinion. According to the U.S. Department of Health and Human Services, your daughter should see a doctor if:

  • She has not gotten her period by the time she is 15 years old.
  • She has not gotten her period within 3 years after breast development or if breasts haven't developed by age 13.
  • Her period suddenly stops for more than 3 months.
  • Her period becomes irregular after they were regular and predictable.
  • Her period occurs more often than 21 days or less often than 45 days.
  • Her period lasts more than 7 days.
  • She is bleeding more heavily than usual or using more than one pad or tampon every 1 to 2 hours.
  • She is bleeding between periods.
  • She experiences severe pain during periods.
  • She suddenly gets a fever or feels sick after using a tampon.

If there is ever a concern about your daughter and her menstrual cycle, talk to a trusted healthcare professional. Sometimes there are underlying hormonal issues or other concerns that your health care provider can address.

5 Sources
Verywell Family uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Karapanou O, Papadimitriou A. Determinants of menarcheReprod Biol Endocrinol. 2010;8:115. doi:10.1186/1477-7827-8-115

  2. ACOG Committee Opinion No. 651: Menstruation in Girls and Adolescents: Using the Menstrual Cycle as a Vital Sign. Obstet Gynecol. 2015;126(6):e143-e146. doi:10.1097/AOG.0000000000001215

  3. American College of Obstetricians and Gynecologists. Your First Period (Especially for Teens).

  4. Allen AM, McRae-Clark AL, Carlson S, et al. Determining menstrual phase in human biobehavioral research: A review with recommendationsExp Clin Psychopharmacol. 2016;24(1):1-11. doi:10.1037/pha0000057

  5. U.S. Department of Health and Human Services. Problem periods.

By Barbara Poncelet
 Barbara Poncelet, CRNP, is a certified pediatric nurse practitioner specializing in teen health.