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What to Know About Your Child’s First Menstrual Period

Disclaimer: This contains no medical advice. Always seek the advice of your physician or other qualified healthcare provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website. This post may contain affiliate links. As an Amazon associate, I may earn a small commission on qualified purchases at no extra cost to you. Full disclaimer here.

The first menstrual period. Menarche. Starting their cycle. Whatever we choose to call it, when someone starts menstruating for the first time, it can feel like a big deal. There are a lot of misconceptions about what to expect the several months right after someone has their first period.

Let’s clear up everything today. The year after the first period starts is unlike any other.

Today, we’ll briefly review what menstrual periods are. Then, we’ll discuss a few things to expect during the first several months after they start. This includes irregular cycles, varying flow, and other symptoms. We’ll go over what to expect at a doctor’s appointment after someone has started their periods. Finally, we’ll conclude with things young adults can do to be empowered, proactive, and healthy after this change.

What is a menstrual period?

For now, let’s define a menstrual period as the uterus (also called a womb) shedding its lining. This means some blood will come out of the vagina. The bleeding usually lasts for a few days. In this post, I’m not going into the biology of why people get periods. A separate post will do that more justice.


When people talk about periods, they also usually talk about something else: ovulation. This is when an egg is released from the ovary and into the fallopian tubes. In most menstruating adults, the timing of periods and ovulation are related. If you know when an adult starts their period, you can roughly guess when they will ovulate (when the egg will be released). This is important when trying to predict all things pregnancy.

However, this relationship between menstrual periods and ovulation is usually not predictable for the 6-12 months after someone starts their periods for the first time. In fact, many kids don’t ovulate at all right after they start their periods. 

What does this all mean? It means menstrual cycles and periods for the first year or so are different  than those of adults. 

What can we expect in that first year after someone’s first period?

First, allow me to emphasize: please do not let any information here delay medical attention. This information is based on population-wide research. Your experience or your child’s experience may be very different. I share here for general knowledge. Research also shows that the more kids know about what to expect with their periods, the less anxious they are. Also, it’s worth noting that there is a need for current and more inclusive research. Much in the past did not include race or ethnicity.

What follows are some typical features of many (not all!) people who have just started menstruating. The average age of menarche (starting period for the first time) is between 12 and 13 years old. Usually, it’s about 2-3 years after breast development starts. In non-Black youth, this hasn’t changed recently. Non-Hispanic Black people are starting their period about 5 months earlier than they did 30+ years ago.

Irregular Cycles

We count a menstrual cycle from the first day of one period to the first day of the next period. If someone has their first period on January 1, and the next one starts on January 28, their cycle is 28 days long. At first, it probably won’t be the same number of days between each period. In fact, most cycles are longer than in adults. This is especially true for the first cycle. The time between the first ever period and the second period may be a lot longer than expected. As time goes on, the length of the cycles becomes shorter. By 3-4 years after starting periods, many people have their expected adult-length cycle (average is between 21-34 days). 

Technically, a “normal” menstrual period is somewhere between 21 and 45 days. For many people, the first cycle can be closer to the 45 days. Overall, the average cycle in the first year is around 32 days.

If at any point (even after the first period), there are more than 90 days between cycles: seek medical care. This is longer than expected and is worth investigating.

2-7 Days of Bleeding

A typical period lasts for 2 -7 days. Brown or red blood is normal. The amount varies from one person to the next. And, research shows that most people aren’t able to guess very well exactly how much they bleed. We do know that soaking & having to change a menstrual product (pad, tampon, or cup) more than every 1-2 hours is “excessive.” This would be another reason to see a doctor. If bleeding lasts for more than 7 days, also seek care.

Period Discomfort

Some periods are uncomfortable. We often hear of cramping pain or PMS. (PMS refers to premenstrual syndrome: mood changes and physical symptoms just before a period starts). Some people also have headaches, nausea, back pain, and fatigue. These more severe symptoms typically start when ovulation has also started, and is coordinated with menstrual periods. As mentioned earlier, this can take several months to sync up. This means that severe symptoms are not expected with the first few periods.

That being said, many still report feeling uncomfortable during their periods even before they’re ovulating. This brings up an important point. If someone has severe pain with their periods during the first few months, there are two important reasons to seek medical care. First, the pain should be addressed! As I’ll discuss more later, periods should not stop someone from doing anything. Secondly, because it’s not common, severe symptoms with the first few periods need to be investigated in order to make sure there’s not another cause for the pain. 

Once someone’s cycle is predictable, any symptoms (cramps, for example) are usually predictable too. There are many safe and effective treatments for these symptoms. It is not a “rite of passage,” to suffer through menstruation. Anyone who is miserable with their periods should seek care. Many swear by home remedies such as heating packs or gentle exercise. These are fine places to start. But, if symptoms persist, please ask for help.

Infographic reading of navy text with three large red splotches on light grey background: What's Normal in a Menstrual Period? It's normal to use about 3-6 pads a day. Typical bleeding lasts 2-7 days. Time from start of one period to the start of the next can be between 21 and 45 days. If something isn't normal or you're not sure ask your doctor! For information only. This is not medical advice.

A Few Frequently Asked Questions About Starting Periods

These are a few of questions I’ve been asked many times by patients or their parents. I’ll also clarify another misconception.

Can someone get pregnant before or just after their first period?

Yes. If someone ovulates (eggs are released), they can get pregnant after having sex. Even though many people are not ovulating predictably, it is absolutely possible. I mention this because we must discuss safe sex and contraception throughout adolescence.

Is it ok for teens to use tampons?

Yes. Menstrual cups are fine too. Washable “period underwear,” or washable pads (affiliate link) are another option too. It’s a personal preference. Many swimmers and other athletes use tampons or cups for their sports. And, to address something else frequently asked: from a medical standpoint, tampons are totally unrelated to virginity.  

What will happen at the doctor’s visit after someone has started their period?

Usually, if there are no major concerns, a pelvic exam is not needed right after someone starts their menstrual period. No Pap test (cancer screening of the cervix) either.  I mention this because I’ve met many girls terrified of this appointment because they’ve been told to expect an invasive exam.

At some point in adolescence, most menstruating teens can be screened for anemia (low blood counts) with a quick blood test. This is to make sure they haven’t lost too much blood with their periods. If someone has anemia related to menstruation, iron supplements may be an option.

(The test may be similar to one-year-olds being screened for anemia).

What can teens do to stay healthy after starting their period?

Adolescence is when children can start to have more ownership of their health. What follows are things they can do to be healthy and informed after starting their menstrual cycle.

Track Cycles

They can keep track of their menstrual cycle, either with a paper calendar or a smart phone app. (Here is a free paper tracker). Make note of the first day of each period to learn cycle length. They can also keep track of how many days each period lasts and any other symptoms.

If Needed: Ask for Help

I encourage (implore!) all teens to ask for help if their period is keeping them from doing anything they want to do. Or should do. If someone is missing school due to their periods, we need to help them. As discussed earlier, there are many safe, easy, and over-the-counter treatments. There are also prescriptions when needed.

(Some people also miss school during their period due to lack of adequate sanitary supplies. This topic of “period poverty,” also merits a separate post, but I mention it here to start to raise some awareness).

Eat Well and Stay Active

Of course, it’s always important to eat well and exercise. In teens, it’s especially important to include: iron, calcium, and vitamin D in the diet. The exercise is good for overall health, but can also help with many period-related symptoms.

If Needed: Ask for Birth Control

Confidentiality laws vary from state to state. Many allow for a teen to talk to a healthcare professional privately about birth control.


After starting their period, most people experience slightly longer and more irregular cycles than adults. It can take a few years to have predictable periods, ovulation, and cycle length. Until then, I encourage everyone to keep track of cycles and ask for help when needed. For many, starting their period is a joyous experience, signifying great things ahead.

Review of Reasons to Seek Medical Care:

  • More than 90 days between cycles
  • Individual periods lasting more than 7 days
  • Soaking through pads or tampons more than every 1-2 hours
  • Excessive bleeding and other symptoms (bruising, family history of bleeding disorder)
  • Cycles consistently out of the 21-45 day range
  • Pain or discomfort

Maya M. Mahmood, D.O., FAAP is a board-certified pediatrician and mom. She is passionate about parents having evidence-based information to help their families be healthier.

Photo by Levi Guzman on Unsplash


ACOG Committee Opinion No. 651: Menstruation in Girls and Adolescents: Using the Menstrual Cycle as a Vital Sign. (2015). Obstetrics and gynecology126(6), e143–e146.

Gunn, H. M., Tsai, M. C., McRae, A., & Steinbeck, K. S. (2018). Menstrual Patterns in the First Gynecological Year: A Systematic Review. Journal of pediatric and adolescent gynecology31(6), 557–565.e6.

Stewart, H. Primary Dysmenorrhea in Adolescents. Winter 2018 Pediatric Forum. Dayton Children’s. via

Carlson, L. J., & Shaw, N. D. (2019). Development of Ovulatory Menstrual Cycles in Adolescent Girls. Journal of pediatric and adolescent gynecology32(3), 249–253.

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