Asked by aiden
When does puberty occur? What causes the changes that occur during puberty?
All Answers 1
Answered by
GPT-5 mini
AI
Short answer
- Puberty usually starts in girls between about 8 and 13 years old and in boys between about 9 and 14 years old. There is wide normal variability; some people start earlier or later.
- The changes of puberty are driven by hormones. The brain (hypothalamus and pituitary), the gonads (ovaries or testes) and the adrenal glands activate and produce hormones (estrogen, testosterone, adrenal androgens, growth hormone/IGF‑1) that cause the physical, emotional and reproductive changes of puberty.
More detail
When puberty begins
- Girls: commonly begins with breast budding (thelarche) around ages 8–13. Menstruation (menarche) usually occurs about 2–3 years after breast development, typically around age 12–13 on average.
- Boys: commonly begin with testicular enlargement around ages 9–14. Voice change, increased muscle mass and facial hair come later.
- The timing varies by genetics, nutrition, body fat, overall health, and environmental influences. If signs start very early (before ~8 in girls or ~9 in boys) or are absent by mid-adolescence (no breast development by 13, no testicular growth by 14), a medical evaluation is recommended.
What causes the changes
- Activation of the hypothalamic–pituitary–gonadal (HPG) axis:
- The hypothalamus begins to release gonadotropin-releasing hormone (GnRH) in a pulsatile pattern.
- GnRH signals the pituitary to release luteinizing hormone (LH) and follicle-stimulating hormone (FSH).
- LH and FSH stimulate the ovaries or testes to produce sex steroids (estrogens and progesterone in ovaries; testosterone in testes).
- These sex steroids cause breast and genital development, growth of body hair, growth spurt, changes in body shape and the ability to reproduce.
- Adrenarche (adrenal maturation):
- The adrenal glands increase production of weak androgens (DHEA, DHEA‑S), which drive pubic and axillary hair, body odor and some skin changes.
- Growth hormone and IGF‑1:
- GH and IGF‑1 levels rise during puberty and produce the adolescent growth spurt and changes in body composition.
What changes occur (examples)
- Primary sexual changes: enlargement/maturation of ovaries and testes; onset of ovulation and menstruation in girls; sperm production in boys.
- Secondary sexual characteristics: breast development, testicular and penile growth, pubic/axillary/facial hair, voice deepening, changes in fat and muscle distribution.
- Rapid linear growth and changes in body composition.
- Skin changes (oiliness, acne), emotional and cognitive changes as the brain matures.
When to see a doctor
- If puberty starts very early (before about 8 in girls or 9 in boys) or if there is no sign of puberty by age 13 in girls or 14 in boys, seek medical evaluation to rule out underlying causes or treatable hormone disorders.
If you want, I can give a simple timeline of typical events for girls and boys, or explain what Tanner stages are.
- Puberty usually starts in girls between about 8 and 13 years old and in boys between about 9 and 14 years old. There is wide normal variability; some people start earlier or later.
- The changes of puberty are driven by hormones. The brain (hypothalamus and pituitary), the gonads (ovaries or testes) and the adrenal glands activate and produce hormones (estrogen, testosterone, adrenal androgens, growth hormone/IGF‑1) that cause the physical, emotional and reproductive changes of puberty.
More detail
When puberty begins
- Girls: commonly begins with breast budding (thelarche) around ages 8–13. Menstruation (menarche) usually occurs about 2–3 years after breast development, typically around age 12–13 on average.
- Boys: commonly begin with testicular enlargement around ages 9–14. Voice change, increased muscle mass and facial hair come later.
- The timing varies by genetics, nutrition, body fat, overall health, and environmental influences. If signs start very early (before ~8 in girls or ~9 in boys) or are absent by mid-adolescence (no breast development by 13, no testicular growth by 14), a medical evaluation is recommended.
What causes the changes
- Activation of the hypothalamic–pituitary–gonadal (HPG) axis:
- The hypothalamus begins to release gonadotropin-releasing hormone (GnRH) in a pulsatile pattern.
- GnRH signals the pituitary to release luteinizing hormone (LH) and follicle-stimulating hormone (FSH).
- LH and FSH stimulate the ovaries or testes to produce sex steroids (estrogens and progesterone in ovaries; testosterone in testes).
- These sex steroids cause breast and genital development, growth of body hair, growth spurt, changes in body shape and the ability to reproduce.
- Adrenarche (adrenal maturation):
- The adrenal glands increase production of weak androgens (DHEA, DHEA‑S), which drive pubic and axillary hair, body odor and some skin changes.
- Growth hormone and IGF‑1:
- GH and IGF‑1 levels rise during puberty and produce the adolescent growth spurt and changes in body composition.
What changes occur (examples)
- Primary sexual changes: enlargement/maturation of ovaries and testes; onset of ovulation and menstruation in girls; sperm production in boys.
- Secondary sexual characteristics: breast development, testicular and penile growth, pubic/axillary/facial hair, voice deepening, changes in fat and muscle distribution.
- Rapid linear growth and changes in body composition.
- Skin changes (oiliness, acne), emotional and cognitive changes as the brain matures.
When to see a doctor
- If puberty starts very early (before about 8 in girls or 9 in boys) or if there is no sign of puberty by age 13 in girls or 14 in boys, seek medical evaluation to rule out underlying causes or treatable hormone disorders.
If you want, I can give a simple timeline of typical events for girls and boys, or explain what Tanner stages are.
Submit Your Answer
We prioritize human answers over AI answers.
If you are human, and you can answer this question, please submit your answer.