Irregular Periods & Beyond: A Well-Woman Care Guide For Ages 13-20 Women

You’re a woman! Well, at least according to science. You typically get your first period between the ages of 12 and 13, which marks the beginning of your reproductive years (i.e., when you can get pregnant). This is a good time to start seeing a gynecologist if you need to talk about irregular periods, contraception or any other questions about womanhood. 

It is also an ideal time to develop healthy habits like eating well, exercising regularly, and seeing your doctor annually for preventive care. During the next few years, you’ll grow a lot physically, mentally and emotionally, and your reproductive and sexual health and well-being are 100% part of that. This new you may have some scary unknowns, but with support and knowledge, you can navigate these changes.  

Understanding Irregular Periods: A Teen’s Guide to What’s Normal (and What’s Not) 

If you’re just starting to navigate your period and feeling confused, don’t worry, you’re not alone.  Menstrual cycles can be unpredictable, especially in your teens, and yet most of us aren’t taught what “irregular” really means. This guide is here to help you understand what’s normal, what’s not, and how to take care of your menstrual health without shame. 

The Menstrual Cycle

First things first: What is your menstrual cycle, what is a period, and what does a “regular” one look like? Let’s quickly break it down: 

• A menstrual cycle is counted from the first day of bleeding in one month to the first day of bleeding in the next month. During the cycle, you experience ovulation, which is when the ovary releases an egg. 
• A period is the release of blood from the uterus through the vagina - it’s absolutely normal and part of the menstrual cycle.  
• The average menstrual cycle is about 28 days, but 21- to 45-day cycles are also normal. 

The entire process is regulated by reproductive hormones, namely estrogen and progesterone. 

What a “Regular” Period Looks Like

Everyone’s cycle is a little different, but there are some general guidelines clinicans use: 

• Most cycles are 24–38 days from the start of one period to the start of the next. 
• A period (the bleeding) usually lasts 3–7 days. 
• Flow can vary from light to heavy, but you shouldn’t need to change pads or tampons more than once every couple of hours. 

 When you first start menstruating, your period may be a little irregular as your hormones find their groove. You may have longer periods that don't always start when you expect them to. But as time passes, your cycles tend to regulate and last between two and seven days. 

What Counts as Irregular? 

“Irregular” isn’t just having a different cycle than your friends. It usually means one of the following: 

• Periods come closer than 24 days apart or more than 38 days apart. 
• Bleeding lasts longer than 7 days, or you’re soaking through pads/tampons every hour. 
• You have spotting between periods or after sex (if you are sexually active) 
• Severe cramps or sudden changes occur after you have a regular cycle 

 If you have any of the above, you should speak with your doctor so they can make sure everything is ok. 

The Medical Terms for Irregular Periods 

Irregular can look at a few different ways, so several medical terms cover it: 

• Oligomenorrhea: Infrequent periods that are more than 35 days apart 
• Amenorrhea: Periods that are absent for 3-6 months or longer 
• Abnormal Uterine Bleeding: A broader term that covers issues such as heavy bleeding, or bleeding between periods. 

What Causes Irregular Periods

If your period doesn’t come at the same time every month, don’t worry - it’s very common in the first few years of your menstrual cycle for a few reasons. 

Puberty and Early Menstruation 

In the first few years after you start menstruating, it’s common to have anovulation (no egg released that month). Without ovulation, cycles can be longer, shorter, or unpredictable. This usually settles down by your late teens. 

Lifestyle and Environmental Factors 

Consider your body as an interconnected system in which each process works in harmony with the others. When one process is disrupted, it can affect the balance and function of the whole system. Things that can disrupt your hormones and menstrual cycle include: 

• Stress and lack of sleep: Exams, sports, or personal stress can affect your cycle. 
• Intense exercise and eating patterns: Exercising too much or not getting enough calories can lead to missing periods. 
• Sudden weight gain or loss: Rapidly gaining or losing weight can affect your hormones and lead to amenorrhea or oligomenorrhea. 

Medical and Hormonal Causes 

Sometimes irregular cycles are linked to medical conditions. Common ones include: 

• Polycystic Ovary Syndrome (PCOS): A hormonal imbalance that can cause irregular or absent periods, acne, and increased hair growth 
• Thyroid dysfunction: Both overactive and underactive thyroid glands can disrupt your cycle. 
• Endometriosis, fibroids, or pelvic infections: These can cause heavy bleeding or pain. 
• Pregnancy or miscarriage: If you’re sexually active and your period is late, take a pregnancy test to be sure. 
   

Medications and Birth Control 

Hormonal contraception (the pill, patch, ring, or hormonal IUD) can also change your bleeding pattern. Sometimes it makes cycles more regular; other times it causes lighter or absent periods. 

Tracking Your Cycle 

Tracking your periods can help you get a sense of patterns and understand what’s normal for you. There are apps for your phone, or you can write it down in a notebook. Keep a record of the date of your first period, how many days it lasted, how heavy or light your bleeding is, and any symptoms like cramps, headaches, or mood swings. 

 Keeping these records helps establish what is normal for your cycle. You can also share this info with your healthcare provider in case something comes up in the future. 

Sexual Health in your Teens 

Some of your friends and peers may start expressing an interest in sex, and it’s critical that you understand that sexual health is also important. Sexually transmitted infections (STIs) can cause uncomfortable or painful symptoms, and some cannot be cured and may have long-term effects. 

 Being sexually active doesn’t only refer to penis-in-vagina (PIV) sex; it also includes oral sex, anal sex, and masturbation, or self-stimulation, including with sex toys and interactions with same sex partners. 

What are STDs/STIs? 

When you are sexually active, you are in contact with another person's bodily fluids, and that puts you at risk for both pregnancy and STIs. You may also hear STIs referred to as STDs, which are sexually transmitted diseases. 

 STIs are spread through sexual contact, either with bodily fluids (i.e., semen, discharge and saliva) or skin-to-skin contact. Some STIs are bacterial infections, and others are viruses. 

STD Signs and Symptoms 

Some common STIs and their signs and symptoms are: 

• Syphilis: A painless sore (called a chancre) in or around your vagina, rectum or mouth and later, a bumpy rash  
• Gonorrhea: Unusual discharge, painful sex, bleeding between periods, pain in the pelvis (NOTE: women commonly do not have symptoms) 
• Chlamydia: Unusual discharge with a smell, painful sex, bleeding between periods, frequent need to pee, pain or burning when you pee 
• Herpes simplex virus (HSV): Sores, bumps, or blisters near the genitals, rectum, or mouth 
• Human immunodeficiency virus (HIV): Flu-like symptoms, though there are often little to no symptoms for months or years 

You may have noticed that some of these STIs have symptoms can be confused with other conditions. That’s why it’s essential to get regularly tested if you are sexually active.  

Human Papillomavirus (HPV) Vaccination 

HPV infections are spread by skin-to-skin contact during sex and can cause genital warts and cervical cancer later in life. Preferably, you’ll want to get the HPV vaccine before becoming sexually active. 

 The HPV vaccine is recommended for preteens, ideally between the ages of 11 and 12, and is approved by the FDA for people ages 9 to 26. “We want to make sure women are properly immunized against HPV as soon as they are eligible,” says Dr. Lauren M. Beasley from Centre OB/GYN. 

STD Testing and Treatment 

It’s normal to have worries about sex and safety, especially as a teen, if you want to maintain privacy. First things first, your OB/GYN is there for you and your wellness; they will not judge you and only want to help. Ask your provider what information they have to share with your parent or guardian and share with them if you are uncomfortable talking about certain details.  

How to Get Tested 

Testing is the only way to confirm whether you have an STI, and if you are sexually active, both you and your partner(s) should regularly get tested. Most testing is very quick and confidential. It often takes just one swab or blood draw for multiple tests at once. Different STDs require different tests, so it is best to ask your doctor which tests you need. 

STD Treatments & Prevention 

Once you get a diagnosis, most STDs are treatable. The most common treatment is antibiotics, which typically takes anywhere from 7 to 10 days.  

 Of course, the best “treatment” is prevention and staying healthy. You do that by: 

• Regular testing if you are sexually active 
• Making sure your partner(s) get tested and they have proof 
• Wear barriers whenever you engage in sexual activity–condoms and dental dams (yes, you can get an STI from oral sex) 

 If you have had unprotected sex or suspect you have an STI for any other reason, make an appointment with your provider as soon as possible. 

Your First OB/GYN Appointment 

The American College of Obstetricians and Gynecologists (ACOG) recommends having your first gynecology visit between the ages of 13 and 15 and yearly after that. This usually coincides with your first period, but if it hasn’t happened by the age of 15, your doctor can help rule out any underlying causes. 

What to Expect at Your First Appointment 

It's normal to be nervous the first time you see a gynecologist. It should ease your mind that pelvic and breast exams are not typically needed before 18 unless you and your provider find it necessary. This first appointment is primarily to help you understand your changing body, talk to you about your periods, and answer questions about sex, birth control, and sexually transmitted infections.  

 Your visit with your provider is confidential. If you would like your parent or guardian to be with you, let your doctor know.  

Helping You Navigate Your Changing Body 

These are big years; there is so much growing, learning, and changing going on. It's all very exciting, but can be confusing too, so no matter the question, never be afraid to ask. Your gynecologist is there to support you, answer questions and guide you to make healthy decisions. If you’re a teen, speak with your parent or guardian about finding a healthcare provider that specializes in women’s health. You can use the search form at the bottom to find a clinician in your area.