Pubertal Changes (Puberty)

How puberty starts

Puberty begins when the hypothalamus in the brain starts releasing gonadotropin-releasing hormone (GnRH) in pulses. This prompts the pituitary gland to release LH and FSH, which stimulate the ovaries to make estrogen or the testicles to make testosterone. Adrenal glands also produce androgens that cause body hair, oily skin and body odor. Genetics, nutrition and body weight influence timing.

Puberty changes in girls

1. Breast budding (thelarche): a small, sometimes tender lump under one or both nipples, usually between 8 and 13. Breasts can grow unevenly at first.
2. Pubic and underarm hair begin.
3. Growth spurt: fastest growth usually happens early, about 1 year after breasts begin.
4. Body shape changes: wider hips and more body fat.
5. Vaginal discharge appears 6 to 12 months before the first period.
6. First period (menarche): on average around 12, usually 2 to 3 years after breast budding. Periods are often irregular for the first 1 to 2 years.
7. Growth slows and stops a few years after the first period.

Puberty changes in boys

1. Testicle enlargement and thinning, reddening of the scrotum: the first sign, usually 9 to 14.
2. Pubic hair and growth of the penis.
3. Growth spurt: later than in girls, often between 13 and 15, with broadening shoulders and increased muscle.
4. Voice deepening and cracking.
5. Facial, underarm and body hair.
6. Erections and wet dreams (nocturnal emissions).
7. Temporary breast swelling (gynecomastia) under one or both nipples in up to half of boys, which usually settles within 1 to 2 years.

Changes in both sexes

• Acne and oily skin and hair. See acne.
• Body odor from developing sweat glands.
• Growth spurt and clumsiness as limbs grow quickly; growing pains.
• Sleep changes: teens naturally fall asleep later.
• Emotional changes: stronger emotions, mood swings, desire for independence, interest in relationships, self-consciousness about appearance.

Tanner stages

Doctors track puberty using five Tanner stages, from stage 1 (pre-pubertal) to stage 5 (adult), based on breast development in girls, genital development in boys, and pubic hair in both.

Early puberty

Signs before age 8 in girls or 9 in boys are called precocious puberty. It is more common in girls and usually has no specific cause, but in boys and very young girls it can be due to brain, adrenal or ovarian or testicular conditions. Early puberty can cause short adult height and emotional difficulties, and medicines can pause it when needed. Isolated early pubic hair or body odor (premature adrenarche) is often harmless but should be checked.

Late puberty

No breast development by 13, no testicle enlargement by 14, or no period by 15 is considered delayed. The most common reason is a family pattern of late development ("late bloomers"), but low body weight, intense athletic training, chronic illness, eating disorders, thyroid or pituitary problems and genetic conditions such as Turner or Klinefelter syndrome can be responsible. See delayed puberty.

Common concerns during puberty

• Irregular or painful periods: common early on; see dysmenorrhea.
• Breast asymmetry in girls and breast swelling in boys: usually temporary.
• Stretch marks from rapid growth.
• Scoliosis: screening during the growth spurt can detect a spinal curve. See scoliosis.
• Body image and mood: support, open conversation and, if needed, professional help.

Supporting a child through puberty

• Talk early, before changes begin, using accurate names for body parts.
• Explain periods, wet dreams and body changes as normal.
• Provide pads or other period products, deodorant and gentle skin care.
• Encourage sleep, physical activity and balanced eating.
• Watch for signs of low mood, anxiety, disordered eating or bullying.
• Keep regular checkups, where doctors track growth and development.

Frequently asked questions

What age does puberty start?

Puberty usually starts between 8 and 13 in girls, with breast budding, and between 9 and 14 in boys, with enlargement of the testicles. Timing varies widely and often follows family patterns. Starting earlier or later than these ranges should be checked by a doctor.

What are the first signs of puberty in girls?

The first sign is usually breast budding: a small, sometimes tender bump under one or both nipples. Pubic hair, a growth spurt and body shape changes follow. Periods usually begin about 2 to 3 years after breast development starts.

What are the first signs of puberty in boys?

The first sign is enlargement of the testicles and thinning of the scrotal skin, often unnoticed. Pubic hair and growth of the penis follow, then the growth spurt, voice deepening and facial hair. Boys usually start and finish puberty about 1 to 2 years later than girls.

Is it normal for periods to be irregular at first?

Yes. In the first 1 to 2 years after the first period, cycles can range from about 21 to 45 days and sometimes skip months, because ovulation is not yet regular. Very heavy bleeding, periods lasting more than 7 days, or no periods for 3 months after they were regular should be checked.

How long does puberty last?

Puberty usually lasts about 3 to 5 years from the first signs to full physical maturity. Girls often finish growing around 15 to 16 and boys around 17 to 18, though some boys continue growing slightly into their early 20s.