Teen Menstrual Cycles: Why Missed Periods, Irregular Periods are Normal

Recently, there has been a flood of questions from my teen readers on my popular post, “Reasons for Missed Period – When You’re Not Pregnant.” I want to address the most commonly asked questions to alleviate any worries that teenagers may have about their periods.

Age of Your First Period

A teenager typically gets her first period between 12 and 14 years of age. Some girls can start menstruating as early as 9 years old. Others won’t have their first period until they’re 16 years of age. When you’ll have your first period depends on how fast you’re developing. Some girls are early bloomers; others bloom later. If you haven’t had your period by 16 years old, visit your doctor and find out what’s the hold up. In some cases, however, it may still be normal.

How Long Does a Period Last?

A regular period can last between three to seven days. During the teen years, you can bleed for even longer. Some teenagers have their period for 10 days! The length of your period can change from month to month. The heaviness and color of your flow will also change from the beginning of your period to the end. On Day 1, 2, and 3 of your period, it’s normal for your flow to be heavy. Your menstrual bleeding will become lighter and lighter until your period ends.

Irregular Menstrual Cycles and Missed Periods are Normal

In the first two years after you start menstruating (having your period), it’s normal for you to experience an irregular menstrual cycle. You may have a period twice in one month, or you may go without a period for two months at a time. Likewise, you may have your period for only 2 or 3 days one month, and the next time you have your period, it lasts for 7 days. This is normal during the teenage years. Your body is influenced by your growth (and puberty is a time of major growth), so this can change your menstrual cycle from month to month.

The length of time that your period lasts, and the amount of blood that you experience is influenced by the level of hormones that your body is manufacturing. Since a teenage girl is growing, her hormones are going to be fluctuating and this can change the amount of blood and the length of your period from one cycle to the next.

In a nutshell, missed periods and irregular periods are normal in the first two years after you start having your period. Your body will eventually develop a regular cycle. The average cycle length is 28 days, but not every woman follows this textbook rule. A regular menstrual cycle can run from 21 days to 35 days (or longer). If you’re a teenager, as long as you have one period every three months, you should be fine. But always call a doctor if you’re worried about anything.

*Very Important* – If you do not want to get pregnant, always use protection when you have sex. The only 100 percent way to protect yourself against STDs and pregnancy is to NOT HAVE SEX. Take it from an oldie – it’s always best to wait and save yourself for that special person.

When Should You Worry about a Missed or Irregular Period?

Missed periods and irregular periods can be normal in teenagers, but you should consult a doctor if you’re a teen and you haven’t had your period for at least three months. This may be a sign of a reproductive problem, like premature ovarian failure.

If you have at least one period within that three month range, you shouldn’t worry. This can be normal, just a byproduct of your fluctuating hormones. Your menstrual cycle will eventually even out, and you will get a normal cycle (although it may not be the perfect 28 day cycle.)

Reasons You May Miss Your Period When You’re Not Pregnant

If you are sexually active and you notice something unusual with your menstrual pattern, there is always a chance that you could be pregnant. Condoms are only 99 percent effective. Birth control pills are only effective if you take them on a regular basis. Skipping a pill can put you at risk for pregnancy.

Other reasons you may experience irregular periods, or missed periods, include excessive exercise, birth control pills, stress, and eating disorders.

Excessive Exercise - If you’re an athlete, you may notice a change in your menstrual cycle if you’re training super hard or exercising all the time. Excessive exercise can result in less bleeding, fewer periods a year, or your periods may stop completely. In most cases, your periods will return to normal within months after you stop participating in the strenuous sport.

If your period has stopped completely and it’s been over six months, you need to go see your doctor to rule out any medical problems.

Birth Control Pills – Sometimes, birth control pills are prescribed to help regulate your period. They can, however, cause you to experience a missed period. Hormonal methods of birth control, which contain the hormone progesterone, can cause you to miss your period.

Stress – Whether you’re in middle school or high school, schoolwork can really stress you out, especially if your parents are putting a lot of pressure on you to succeed. Stress is a normal part of life, but a ton of emotional stress can affect your period. Too much stress in your life may cause you to experience missed periods or irregular periods.

Eating Disorders – If you have an eating disorder, like anorexia or bulimia, they can slow down your bodily functions and cause your period to stop completely. Please contact a doctor or reach out to an adult if you have an eating disorder. You can also reach out to me, and I’ll be here to help you through this to the best of my ability.

PMS Symptoms Can Be Similar to Early Pregnancy Symptoms

If you’re a teenager who is sexually active, you must be aware that there is always a chance that you may be pregnant. A missed period is often one of the first signs of pregnancy. Please take a home pregnancy test, if you are ever worried. If you test negative at first, and your period still doesn’t come, take another test in about a week or so.

Always keep in mind, however, that premenstrual (PMS) symptoms can mimic early pregnancy symptoms. Even for the most experienced woman, it can be difficult to distinguish the two. For example, breast tenderness, fatigue, and food cravings are normal PMS symptoms, but they are also pregnancy symptoms. Nausea and vomiting can also affect you when you’re PMSing, and it’s an early pregnancy symptom. Taking a home pregnancy test is the only way for you to tell whether or not you’re pregnant.

For more, read PMS or Pregnancy Symptoms?

If you liked this helpful post, please consider donating to the maintenance of this website. This is a one-person operation, and it takes a lot of time and energy to devote to it. Thanks in advance!

You May Also Enjoy Reading…

How Accurate are Home Pregnancy Tests? – Read about the accuracy of home pregnancy tests, how they work, how soon they can detect a pregnancy, and other helpful info.

Pregnancy Symptoms: 5 Signs That You May Be Pregnant - Learn about the five early signs of pregnancy, when they begin to appear, and what causes them.

My Recommendations for Accurate Home Pregnancy Tests

If you’re wondering whether or not you’re pregnant, please check my Hip Chick’s Guide to Pregnancy and Baby Store for my recommended home pregnancy tests. I highly recommend  First Response Early Result Pregnancy Test due to its high sensitivity at picking up hCG levels.

About DP Nguyen

DP Nguyen is founder and editor of Hip Chick's Guide to PMS, Pregnancy and Babies. She’s an expert pregnancy and women’s health blogger, and she’s available for blog consultation, ghost writing, and general writing services. She is NOT a medical doctor and does NOT offer medical advice. A graduate of Vanderbilt University, DP spends her free time writing children’s novels and loving on her dog, Gracie Lu. Connect with her on Twitter and Facebook.