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Ages & Stages

Physical Development in Girls: What to Expect During Puberty

Two young girls smiling Two young girls smiling

By: Brittany Allen, MD, FAAP & Katy Miller, MD, FAAP

Puberty often begins earlier than parents think―especially in girls.* You can help your daughter navigate this time by learning about these changes and starting conversations about them early.

Here's an overview of the major physical changes girls can expect as they go through puberty:

Breast Development

Girls usually begin puberty between the ages of 8 and 13 years old. The earliest sign of puberty in most girls is the development of breast "buds," nickel-sized bumps under the nipple. It is not unusual for breast growth to start on one side before the other. It's also common for breast buds to be somewhat tender or sore. Uneven breast growth and soreness are both totally normal and usually improve with time.

Body Hair

Coarser hair will begin to grow in the genital area, under the arms, and on the legs. In some girls (about 15%), pubic hair may be the first sign of puberty―showing up before breast budding starts.

A word about shaving

Around the time they reach middle school, many girls begin to show interest in shaving their legs and armpits. This is a personal choice; there is no medical reason to shave armpit or leg hair. Before giving them a razor, show them how to use it properly and avoid skin irritation and cuts, which can become infected. Some tips:

  • Wet the skin & use lotion or gel. Shaving dry skin can scratch and irritate it. It may be easiest to shave in the shower or bathtub when the skin is already wet. Shaving gel, lotion, or cream acts as a buffer on the skin and can help avoid cuts.

  • Use light pressure. Pressing too hard on the razor could shave off some of the skin.  Use extra care around the knees and ankles to avoid nicking the skin.

  • Replace the razor or its blade often. A dull blade is more likely to tug, scrape and irritate the skin.

  • Don't share razors. Sharing a razor can spread bacteria such as Staphylococcus aureus and cause skin infections.

  • Electric razors. Some electric razors are designed specifically for girls. These may be less likely to cut the skin, although they can still cause irritation.

Vaginal Discharge

Some girls experience a small to moderate amount of clear or white vaginal discharge that starts about 6-12 months before their first period. This is a normal response to growing amounts of the hormone estrogen in the body. 


While timelines can vary, most girls get their first period within 2 – 3 years after the development of breast buds. The average age for girls to get their first period in the United States is around age 12. It's important to emphasize that periods are a normal part of growing up. Young girls should know that it's okay to talk about periods and ask questions about them.  Some young people may have anxiety about how to handle their first period, given that it can happen unexpectedly.  Providing supplies (pads, tampons, and pantiliners) for your child's locker or backpack and reviewing resources at school, including the school nurse, can help alleviate this worry.

While some girls will have bright red blood with their first period, other girls may only have spotting with red-brown discharge―both are normal!  While some people will have periods once a month, periods may be irregular in the first few years as the body adapts to rapid physiological changes.  Also, normal cycles of periods can be as short as 21 days or as long as 35… so even people with regular cycles might not have a period every single month!

Abdominal cramping or pain with periods is also common. For most people, ibuprofen or naproxen used as needed are the best medicines to help with period cramps. If menstrual cramps are severe or causing your child to miss school, talk to your pediatrician about other options.

Increase in Height

Most girls have their growth spurt at a younger age than boys do. The fastest rate of height growth usually occurs in girls between when breast buds start to develop and about 6 months before they get their period. Once a girl has had her first period, her growth has already started to slow down. Most girls grow another 1-2 inches after getting their period, but increased height beyond that is less common.

Wider Hips

Her hips will get wider and her waist may get smaller.

Other Common Changes

Many young people develop acne during puberty. This can be related to changes in hormone levels during this time. Sweating under the armpits and increased body odor are also normal changes―and why most girls begin using deodorants and/or antiperspirants at the start of puberty. With more oil and sweat being made by the skin, girls this age may start wanting to shower or shampoo their hair more often.

On occasion, girls start puberty either very early or very late. Contact your pediatrician if you begin to see pubertal changes before your daughter is age 8. Likewise, contact your pediatrician if there are no pubertal changes in your daughter by age 13.

Parent FAQs about girls & changing bodies:

I've heard that girls are getting their periods at younger and younger ages. Is this true?

There is some debate on this. The short answer to this question: maybe. It's clear that the starting age for puberty has decreased over the last 150 years, likely related to improved nutrition. Trends in puberty over the last 40 years are less clear. Some studies suggest that puberty is starting earlier in the United States and Europe. 

Earlier puberty can be seen in children who were born very small as infants (called small for gestational age), and we don't fully understand why this happens. Obesity is also a risk factor for earlier puberty, in part because body fat is involved in how the body processes hormones like estrogen.  

Overall, more information and research is needed on this topic so we can fully understand these patterns and the possible reasons behind them.

My daughter is worried about gaining weight during puberty. Is weight gain part of normal puberty?

Yes. As youth are growing taller, it's normal to gain weight. Rising amounts of estrogen in the body also cause fat to deposit in the hips and breasts, and the overall percentage of body fat increases in girls as they go through puberty. Weight gain that is more than expected during puberty could be a cause for concern, though. Your pediatrician will look for whether your child's weight gain crosses percentile lines on her growth chart or whether her body mass index (BMI) is greater than the 85th percentile. However, the overall pattern of weight gain is more important than any particular number. 

When thinking about healthy lifestyle and weight gain, remember that habits like physical activity and healthy eating develop very early―the same goes for the development of unhealthy food preferences and too much screen time. Ask your pediatrician for ideas on how to incorporate healthy habits into your family's everyday routines. 

I want my 9-year-old daughter to be prepared for her first period, but she's so young! When should I start talking to her about periods?

In general, most girls get their periods an average of 2 – 2 ½ years after the development of breast buds. The development of breast buds is a great opportunity to talk more about body changes yet to come. Emphasize that periods are normal, are part of having a healthy body, and are nothing to be ashamed or embarrassed about. Girls may feel apprehensive about painful periods or anxious that their classmates will find out. While every girl is different, a reassuring approach and adequate information can often relieve some of the anxiety girls may feel about periods. 

It's much better for your daughter to be informed about her body early on in the process of puberty than to be surprised or even scared as these changes happen.  It can also be helpful to have sanitary napkins available ahead of time and explain how to use them before her first period arrives.

Talk openly and honestly about puberty. Answer any questions she may have about the changes in her body. You may not have to know every answer, but know pediatricians are great resources for any questions about puberty that you or your child have along the way! 

When should my daughter have a pelvic exam?

Healthy adolescents do not need a pelvic exam until they are 21 years old. In the past, annual pelvic exams with pap smears were recommended for teenagers who were sexually active, but research has shown that this is not necessary. Pap smears look for evidence of human papilloma virus (HPV) infection, which can cause pre-cancerous and cancerous changes to the cervix. We've learned more and more about HPV in recent years, including that adolescents are much more likely to clear the HPV infection on their own, without need for medical intervention. Pap smears before age 21 are only recommended for very special cases, such as adolescents with HIV or immune deficiencies. Pelvic exams are not done as part of routine health care but may be necessary in certain situations: for example, if a sexually active adolescent has abdominal pain.  

When should girls be taught how to perform self-breast exams? Will her pediatrician talk with her about this?  

Teenage girls generally do not need to perform breast self-exams because they are at extremely low risk of breast cancer. Also, their breasts are likely to change as they grow, and the development of tenderness and swelling can be normal during changes in the menstrual cycle. These normal changes can sometimes lead to anxiety for girls who are performing regular breast exams. Research also has not shown a benefit from breast self-exams in the diagnosis of breast cancer. Currently, we do not recommend routine breast self-exams for pediatric patients, and there are differing guidelines for the recommendations for adults. 

How do I respect my daughter's need for privacy while also monitoring her development?

Offer your daughter opportunities to talk about puberty and the changes that come with it.  Talking openly about puberty can help prevent shame and stigma, and may encourage your daughter to be more willing to talk to you about what she is experiencing. However, some kids simply don't want to talk to their parents about this kind of thing, and that's okay too. Make sure your daughter knows that you're available if she has any questions and that she has access to trusted resources for information. These include books and appropriate health education at school. If you have specific concerns about your child's development or progression through puberty, your pediatrician would be happy to address them with you and your daughter.

Remember: Talking about puberty should not just be a one-time discussion.

Information can be shared in smaller conversations, opening the door for ongoing communication so that your daughter can ask questions at her own pace. This open door will help with conversations about other important topics down the road such as healthy relationshipssex, sexuality, consent, and safety (such as how to prevent sexually transmitted infection and pregnancy, and substance use). Build a good framework early for discussions later. 

*This article reviews the changes that females typically undergo in puberty. Though we use the word "girls," it's important to recognize that not all kids with female bodies identify as girls, and puberty can be a particularly stressful time for kids who are transgender, nonbinary or gender diverse. More information is available about that here.

Additional Information:

About Dr. Allen:

Dr. Britanny AllenBrittany Allen, MD, FAAP, is a board-certified general pediatrician and provides specialty care to transgender and gender nonconforming youth. She is an Assistant Professor of Pediatrics at the University of Wisconsin School of Medicine and Public Health. She is a member of the American Academy of Pediatrics Section on Section on Lesbian, Gay, Bisexual, and Transgender Health and Wellness and the Wisconsin Chapter.

About Dr. Miller:

Dr. Kathleen Kenney MillerKathleen Kennedy Miller, MD, FAAP, is a board-certified pediatrician and current fellow in Adolescent Medicine at the University of Minnesota. Within the American Academy of Pediatrics, she is a member of the Section on Adolescent Health, the Section on Lesbian, Gay, Bisexual, and Transgender Health and Wellness, and the Section on Community Pediatrics.  She is also a member of the Minnesota Chapter.

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American Academy of Pediatrics (Copyright © 2019)
The information contained on this Web site should not be used as a substitute for the medical care and advice of your pediatrician. There may be variations in treatment that your pediatrician may recommend based on individual facts and circumstances.
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