Puberty: Body Changes, Signs & Development Stages

What Is Puberty and When Does It Start?

Puberty is the biological process during which a child's body matures into an adult body capable of sexual reproduction. It typically begins between ages 8-13 in those with female bodies and 9-14 in those with male bodies, lasting 4-6 years. The timing is primarily determined by genetics, meaning children often follow similar patterns to their parents.

Puberty represents one of the most significant developmental transitions in human life. During this period, the body undergoes dramatic changes driven by hormonal shifts that affect virtually every organ system. The hypothalamus in the brain begins releasing gonadotropin-releasing hormone (GnRH) in pulses, which signals the pituitary gland to produce luteinizing hormone (LH) and follicle-stimulating hormone (FSH). These hormones then stimulate the gonads (ovaries or testes) to produce sex hormones—primarily estrogen in those with ovaries and testosterone in those with testes.

The precise trigger for puberty's onset remains an area of active research, but scientists understand that it involves complex interactions between genetic programming, nutritional status, body composition, and environmental factors. Leptin, a hormone produced by fat cells, appears to play a permissive role, signaling that the body has sufficient energy reserves to support reproductive function. This helps explain why severe malnutrition can delay puberty, while obesity may be associated with earlier onset.

Individual variation in pubertal timing is substantial and usually represents normal biological diversity rather than a medical concern. However, the experience of puberty can feel isolating for young people who develop earlier or later than their peers. Understanding that this variation is normal—and that everyone eventually completes puberty—can help reduce anxiety during this transitional period.

The Role of Hormones in Puberty

Hormones are chemical messengers produced by endocrine glands that travel through the bloodstream to target tissues throughout the body. During puberty, several key hormones work together to orchestrate physical development. Estrogen promotes breast development, fat distribution to hips and thighs, and menstrual cycle regulation in those with female bodies. Testosterone drives muscle mass increase, voice deepening, facial hair growth, and genital development in those with male bodies. Both hormones are present in all bodies, just in different proportions.

Growth hormone and insulin-like growth factor 1 (IGF-1) work alongside sex hormones to produce the pubertal growth spurt. Adrenal hormones contribute to pubic and axillary hair growth in all individuals. The interplay of these hormones creates the characteristic physical changes of puberty while also affecting mood, energy levels, and sleep patterns.

How Long Does Puberty Last?

Puberty typically lasts 4 to 6 years from the first signs to complete physical maturity. The process occurs in stages, with different body systems developing at different times. While the sequence of changes is predictable, the rate at which they occur varies considerably between individuals.

The duration of puberty encompasses multiple overlapping developmental processes, each with its own timeline. Breast development in those with female bodies, for example, typically progresses over 3-4 years from the first appearance of breast buds to adult breast shape. The growth spurt peaks about 2 years after the first signs of puberty and concludes when the growth plates in bones fuse, typically 2-3 years after peak height velocity.

For those with female bodies, menarche (the first menstrual period) usually occurs about 2-2.5 years after breast development begins, typically around age 12-13. However, it can occur anywhere between ages 10 and 16 and still be within normal range. Initial menstrual cycles are often irregular as the hormonal feedback system matures, and it may take 1-2 years before a regular cycle establishes.

For those with male bodies, voice changes typically begin around age 13-14 and complete over 1-2 years. The period of voice "cracking" or instability occurs as the larynx grows and the vocal cords lengthen. Facial hair usually appears later in puberty, often not reaching adult patterns until the late teens or early twenties. Testicular and penile growth occurs over several years, with adult size typically reached by late adolescence.

Importantly, puberty isn't a race, and completing it faster or slower than peers has no bearing on ultimate physical development or health. Young people who start puberty later often catch up in height and development by their late teens, though the experience of being a "late bloomer" can be emotionally challenging during the middle school and early high school years.

What Physical Changes Happen During Puberty?

During puberty, the body grows taller, body composition changes, secondary sexual characteristics develop, skin and hair become oilier, and sweating increases. In those with female bodies, breasts develop, hips widen, and menstruation begins. In those with male bodies, the voice deepens, shoulders broaden, facial hair grows, and the genitals enlarge.

The physical changes of puberty are extensive and affect virtually every body system. Understanding these changes helps young people recognize what's happening to their bodies and anticipate what's coming. While every individual's experience is unique, the general pattern of changes is remarkably consistent across populations and cultures.

Growth and Body Shape Changes

The pubertal growth spurt is one of the most dramatic changes, with peak growth rates of 8-10 centimeters per year in those with female bodies and 9-11 centimeters per year in those with male bodies. This accelerated growth doesn't affect all body parts equally—hands and feet often grow first, followed by arms and legs, then the trunk. This asynchronous growth pattern explains why adolescents sometimes appear gangly or uncoordinated.

In those with female bodies, estrogen promotes fat deposition in the breasts, hips, thighs, and buttocks, creating the typical adult female body shape. The pelvis widens to accommodate potential future childbearing. Muscle development also increases, though typically less dramatically than in those with male bodies.

In those with male bodies, testosterone drives significant increases in muscle mass and strength, broader shoulders, and a narrower hip-to-shoulder ratio. The jaw and forehead become more prominent. Body fat percentage typically decreases as muscle mass increases.

Breast Development

Breast development (thelarche) is usually the first visible sign of puberty in those with female bodies, typically beginning between ages 8-13. The process begins with breast buds—small mounds beneath the nipples that may initially be tender or uncomfortable. Breast development progresses through recognized stages (Tanner stages 1-5) over approximately 4 years.

It's entirely normal for breasts to develop asymmetrically, with one breast becoming noticeable before the other. While some asymmetry often persists into adulthood, the difference usually becomes less pronounced as development completes. The final breast size is determined primarily by genetics and cannot be predicted from the rate or timing of initial development.

Those with male bodies may also experience some breast tissue development (gynecomastia) during puberty due to hormonal fluctuations. This typically appears as a small, sometimes tender lump beneath one or both nipples and usually resolves within 1-3 years. True gynecomastia affects up to 70% of adolescent males and is considered a normal variant of puberty in most cases.

Hair Growth

New hair growth during puberty occurs in predictable locations. Pubic hair typically appears first, beginning as sparse, soft hair that gradually becomes coarser and covers a larger area. Axillary (underarm) hair usually follows about a year later. Hair may also increase on arms, legs, and other body areas.

In those with male bodies, facial hair development follows a typical progression: first appearing on the upper lip, then spreading to the cheeks, chin, and finally the neck. Full beard development may not complete until the mid-twenties. Chest, back, and abdominal hair may also develop, with significant individual variation in amount and pattern.

Hair on the head often becomes oilier during puberty as sebaceous glands become more active. This increased oil production affects both hair and skin and is driven by rising androgen levels.

How Does the Reproductive System Develop?

During puberty, the reproductive organs grow and mature to enable fertility. In those with female bodies, the uterus and ovaries enlarge, menstruation begins, and the vulva changes in appearance. In those with male bodies, the testes and penis grow, sperm production begins, and ejaculation becomes possible. These changes signal the beginning of reproductive capability.

The reproductive system undergoes perhaps the most fundamental transformation during puberty, changing from a dormant, immature state to full reproductive capability. These changes are driven by sex hormones and follow predictable developmental sequences, though as with all aspects of puberty, individual timing varies.

Changes in Those with Female Bodies

Internal reproductive organs undergo significant growth and development during puberty. The uterus increases dramatically in size, and the endometrial lining develops the capacity to thicken and shed cyclically—the basis for menstruation. The ovaries grow and begin the cyclical process of follicle maturation and ovulation, though regular ovulatory cycles may not establish for 1-2 years after menarche.

External genital changes include growth and maturation of the labia (both inner and outer), which may become larger and change in color. The clitoris also grows. Vaginal discharge (leukorrhea) often appears 6-12 months before menarche as the vaginal lining matures and begins producing secretions that maintain vaginal health and pH balance.

Menstruation typically begins 2-2.5 years after breast development starts, with the average age of menarche around 12.4 years in well-nourished populations. Early cycles are often irregular and may be anovulatory (occurring without ovulation). It can take 1-2 years for cycles to become regular, and significant variation in cycle length is normal during adolescence.

Changes in Those with Male Bodies

Testicular growth is the first sign of puberty in those with male bodies, beginning with an increase in testicular volume that may not be visible but can be measured by healthcare providers. The testes begin producing testosterone and developing the capacity to produce sperm. Full sperm production (spermarche) typically begins around age 13, though this isn't externally visible.

The penis grows in length first, then in circumference. Final adult size is typically reached by late adolescence, though there's considerable normal variation. The scrotum grows, becomes more textured, and often darkens in color. The foreskin becomes more retractable.

Ejaculation becomes possible as the reproductive tract matures. Many adolescents experience spontaneous nocturnal emissions ("wet dreams")—ejaculation during sleep—which is a normal part of pubertal development. These occur in nearly all males during puberty and do not indicate sexual thoughts or behaviors.

Natural secretions (smegma) form beneath the foreskin and between the labia. This is a normal bodily secretion, though it does require regular cleaning as part of good hygiene practices.

Why Does Skin Change During Puberty?

Rising hormone levels during puberty stimulate sebaceous glands to produce more oil (sebum), leading to oilier skin and hair. This increased oil production, combined with dead skin cells, can clog pores and cause acne. Nearly 85% of adolescents experience some degree of acne during puberty, making it the most common skin condition in this age group.

Skin changes during puberty reflect the body's response to rising androgen levels, which affect sebaceous glands throughout the body. These changes are among the most visible and sometimes most distressing aspects of puberty, though understanding their cause can help normalize the experience.

Sebaceous glands, which are attached to hair follicles, enlarge and increase their production of sebum—an oily substance that normally helps protect and moisturize the skin. During puberty, sebum production can increase significantly, particularly in areas with high concentrations of sebaceous glands: the face (especially the T-zone of forehead, nose, and chin), chest, upper back, and shoulders.

Acne develops when sebum and dead skin cells accumulate in hair follicles, creating an environment where Cutibacterium acnes (formerly Propionibacterium acnes) bacteria can thrive. The body's inflammatory response to these bacteria produces the redness, swelling, and pus associated with inflammatory acne. Non-inflammatory acne (blackheads and whiteheads) results from clogged pores without significant bacterial involvement.

Managing Skin Changes

Good skin care during puberty focuses on gentle cleansing, avoiding harsh products that strip natural oils (which can paradoxically increase oil production), and using non-comedogenic moisturizers and sunscreens. Over-the-counter acne treatments containing benzoyl peroxide, salicylic acid, or adapalene can effectively manage mild acne. More severe or persistent acne may benefit from prescription treatments, including topical retinoids, antibiotics, or hormonal therapies.

It's important to avoid picking or squeezing pimples, as this can worsen inflammation, introduce bacteria, and increase the risk of scarring. Acne is not caused by poor hygiene, and excessive washing can actually irritate the skin and worsen breakouts. Most adolescent acne improves in the late teens and early twenties as hormone levels stabilize.

What Hygiene Changes Are Needed During Puberty?

Puberty brings increased sweating and body odor as apocrine sweat glands become active, requiring daily bathing and the use of deodorant or antiperspirant. Hair becomes oilier and may need more frequent washing. Menstrual hygiene products become necessary for those who menstruate. Establishing good hygiene habits during puberty supports both physical health and social confidence.

The hygiene needs of adolescents differ significantly from those of younger children due to the activation of apocrine sweat glands and increased sebaceous gland activity. Apocrine glands, located in the armpits, groin, and other areas, produce a thicker sweat that, when broken down by skin bacteria, creates the characteristic "body odor" associated with adolescence and adulthood.

Daily bathing or showering becomes more important during puberty to remove sweat, bacteria, and excess oil. Particular attention should be paid to areas where apocrine glands are concentrated: armpits, groin, and feet. Using soap or body wash effectively removes bacteria that cause odor, while deodorants mask odor and antiperspirants reduce sweating by temporarily blocking sweat glands.

Hair typically needs more frequent washing during puberty due to increased scalp oil production. However, washing daily isn't necessary for everyone and can sometimes cause the scalp to produce even more oil. Finding the right washing frequency—often every other day or every 2-3 days—varies by individual hair type and activity level.

Menstrual Hygiene

Those who menstruate need to learn about and have access to menstrual hygiene products. Options include disposable pads and tampons, reusable cloth pads, menstrual cups, and period underwear. Each option has advantages and disadvantages, and preference often comes down to individual comfort, activity level, and access.

Key menstrual hygiene practices include changing pads or tampons regularly (at least every 4-8 hours), washing hands before and after changing products, and proper disposal of used products. Tampons should be changed every 4-8 hours to reduce the rare but serious risk of toxic shock syndrome (TSS).

Why Do Emotions Change During Puberty?

Emotional changes during puberty result from hormonal effects on brain chemistry, ongoing brain development, and the psychological challenges of adolescence. Mood swings, increased emotional intensity, heightened self-consciousness, and new social and romantic feelings are all normal aspects of pubertal development. The prefrontal cortex, which regulates emotional responses, continues developing until the mid-twenties.

The emotional landscape of puberty can feel like a rollercoaster, with intense highs, sudden lows, and unpredictable shifts. These experiences, while sometimes overwhelming, are rooted in biology and represent normal developmental processes. Understanding the science behind emotional changes can help young people and their families navigate this period with greater compassion and patience.

Sex hormones directly influence brain chemistry, affecting neurotransmitters like serotonin, dopamine, and norepinephrine that regulate mood, motivation, and emotional responses. Estrogen, for example, affects serotonin receptors and can influence mood stability; fluctuations in estrogen levels during the menstrual cycle often correlate with mood changes. Testosterone can increase reactivity to perceived threats and may contribute to irritability.

Simultaneously, the adolescent brain is undergoing major structural remodeling. The prefrontal cortex—responsible for decision-making, impulse control, and emotional regulation—doesn't fully mature until the mid-twenties. Meanwhile, the limbic system, which processes emotions, is highly active. This developmental mismatch can result in strong emotional reactions that are difficult to regulate.

Common Emotional Experiences

Most adolescents experience some combination of mood swings (rapid shifts between happiness, sadness, or anger), increased sensitivity to criticism or perceived rejection, heightened self-consciousness about appearance and social standing, new romantic and sexual feelings, desire for greater independence and autonomy, and questioning of identity, values, and beliefs.

These experiences are so universal that they represent normal adolescent development rather than problems to be solved. However, the intensity and persistence of certain feelings should be monitored. Severe or prolonged depression, anxiety that interferes with daily functioning, thoughts of self-harm, or other concerning symptoms warrant professional evaluation.

Supporting Emotional Development

Parents and caregivers can support emotional development by maintaining open, non-judgmental communication; acknowledging that adolescent emotions are real and valid; providing consistent boundaries while respecting growing autonomy; modeling healthy emotional expression and coping strategies; and ensuring adequate sleep, nutrition, and physical activity—all of which affect mood regulation.

How Does the Voice Change During Puberty?

Voice changes occur in all adolescents as the larynx grows under the influence of hormones. In those with male bodies, testosterone causes significant laryngeal growth, producing voice "cracking" and ultimately a deeper voice about an octave lower than before. In those with female bodies, voice changes are more subtle, with the voice deepening by about three semitones on average.

The voice change during puberty—colloquially called the "voice breaking" or "voice cracking" period—results from growth of the larynx (voice box) and lengthening of the vocal cords. This transformation is more dramatic in those with male bodies due to the effects of testosterone, but occurs to some degree in everyone.

In those with male bodies, the larynx increases in both width and length, and the vocal cords can nearly double in length. During this growth period, which typically lasts 3-6 months but can extend to a year, the voice may be difficult to control. It may crack, squeak, or suddenly shift between higher and lower pitches mid-sentence or mid-word. This is caused by the brain's vocal control centers adapting to the rapidly changing instrument.

The characteristic "Adam's apple"—a visible protrusion in the front of the throat—develops as the larynx grows forward. While often associated with male bodies, some people with female bodies also have a visible laryngeal prominence.

For those with female bodies, laryngeal growth is less pronounced, and voice changes are often barely noticeable. The voice typically deepens slightly, becomes somewhat richer in tone, and may have slightly expanded range. These changes usually occur gradually without the dramatic cracking experienced by those with more significant laryngeal growth.

When Should You Consult a Healthcare Provider?

Consult a healthcare provider if puberty begins before age 8 in those with female bodies or age 9 in those with male bodies (precocious puberty), or if there are no signs of puberty by age 13 in those with female bodies or age 14 in those with male bodies (delayed puberty). Also seek guidance for severe acne, menstrual problems, significant emotional distress, or concerns about body image and gender identity.

While most variations in pubertal timing and progression are normal, some situations warrant medical evaluation. Early identification of underlying conditions allows for appropriate intervention when needed and provides reassurance when development falls within normal ranges.

Precocious Puberty

Precocious (early) puberty is defined as the appearance of secondary sexual characteristics before age 8 in those with female bodies or age 9 in those with male bodies. While sometimes simply representing the early end of normal variation, precocious puberty can occasionally indicate underlying conditions that require treatment. Early puberty can also have psychological impacts and may result in shorter adult height if not addressed, as early closure of growth plates can limit final height.

Central precocious puberty results from early activation of the hypothalamic-pituitary-gonadal axis and can be treated with GnRH analogs that temporarily pause pubertal progression. Peripheral precocious puberty results from sex hormone production from other sources and requires different treatment approaches.

Delayed Puberty

Delayed puberty is generally defined as the absence of breast development by age 13 in those with female bodies or the absence of testicular enlargement by age 14 in those with male bodies. Constitutional delay of growth and puberty (CDGP)—a normal variant where puberty simply starts later—is the most common cause, especially if there's a family history of late development.

However, delayed puberty can sometimes indicate underlying conditions including hormonal deficiencies, chronic diseases, eating disorders, or genetic conditions. Evaluation typically includes a thorough history, physical examination, bone age X-ray, and blood tests to assess hormone levels.

Other Reasons to Consult a Provider

• Severe or scarring acne that doesn't respond to over-the-counter treatments
• Menstrual concerns including absence of periods by age 15-16, periods that are extremely painful or heavy, or cycles that haven't become somewhat regular 2-3 years after menarche
• Signs of hormonal imbalances such as excessive hair growth, significant hair loss, or marked menstrual irregularities
• Emotional or mental health concerns including persistent depression, anxiety, eating disorders, or thoughts of self-harm
• Concerns about gender identity—specialized providers can discuss options and provide support

How Can Parents Support Children Through Puberty?

Supporting children through puberty involves starting conversations early, providing accurate information, normalizing the experience, offering practical help with new hygiene needs, remaining approachable despite potential awkwardness, respecting growing independence while maintaining connection, and monitoring for signs that professional support might be helpful.

Parents and caregivers play a crucial role in helping young people navigate puberty successfully. Children who receive accurate information and emotional support from trusted adults tend to adjust better to pubertal changes and are more likely to come to adults with concerns or questions.

Starting conversations about puberty before it begins—ideally around age 8-9—helps prepare children for upcoming changes and establishes you as a trustworthy source of information. Use accurate anatomical terms, answer questions honestly and age-appropriately, and create opportunities for ongoing dialogue rather than treating puberty as a one-time conversation.

Practical support matters too. Ensure adolescents have access to appropriate hygiene products (deodorant, menstrual products, skincare as needed), comfortable clothing that accommodates changing bodies, and private space for changing and bathing. Respect their growing need for privacy while remaining available and approachable.

Emotional support is equally important. Acknowledge that the changes and feelings of puberty are real and valid. Avoid dismissing concerns as "just hormones" even when hormones are indeed a factor. Listen more than you lecture. Share your own experiences of puberty when appropriate—knowing that adults went through similar experiences can be reassuring.

Helpful Conversations to Have

Beyond the basics of physical changes, consider discussing body image and media literacy, helping young people critically evaluate unrealistic images in media and advertising. Talk about consent, boundaries, and healthy relationships before they become immediately relevant. Discuss the emotional aspects of puberty, normalizing mood changes while also identifying when professional help might be useful. Address topics like substance use, which often becomes relevant during adolescence.