Signs of Puberty

Puberty begins with increased pulses of Gonadotropin-releasing hormone (GnRH) from the hypothalamus, which stimulate the pituitary gland to release Luteinizing hormone (LH) and Follicle-stimulating hormone (FSH). These hormone pulses initially occur during sleep but gradually extend into waking hours over three to four years, fully activating the hypothalamic-pituitary-gonadal axis and establishing adult reproductive hormone patterns.

Testosterone stimulates the maturation of accessory glands of the male reproductive system, including the prostate and seminal glands, and promotes spermatogenesis. It also triggers growth of the larynx and vocal cords, causing voice deepening, and stimulates skeletal muscle growth, increasing strength and endurance. Additionally, testosterone converts to estrogen, which is essential for closing epiphyseal cartilage and limiting height growth.

Estrogen targets the uterus, promoting myometrium thickening and increased endometrial blood flow. It also stimulates functional development of accessory reproductive organs including the breasts, fallopian tubes, and vaginal epithelium, while promoting cervical mucus production. These changes prepare the reproductive system for menstruation and fertility.

After menarche, ovulation occurs in only about 10% of menstrual cycles initially, and the luteal phase is shorter than the typical 14 days. Over one to two years, the percentage of ovulatory cycles gradually increases and the luteal phase lengthens to its standard duration. This gradual stabilization reflects the ongoing maturation of the hormonal regulation of the menstrual cycle.

Puberty typically begins around ages 8 to 13 in females and 9 to 14 in males, though timing varies based on genetics, environmental factors, and overall health. This period marks the onset of reproductive maturity and is characterized by the development of secondary sexual characteristics and the attainment of reproductive potential.

Both testosterone and estrogen accelerate bone deposition and skeletal growth during puberty. However, they also promote closure of epiphyseal cartilages, which caps height growth. Girls generally do not grow as tall as boys because puberty begins earlier in females, leading to more rapid estrogen-induced epiphyseal cartilage closure.

Fat distribution patterns diverge at puberty due to the effects of androgens in males and estrogens in females. Males tend to accumulate subcutaneous fat at the neck, arms, lower back, and buttocks, while females store it predominantly at the breasts, buttocks, hips, and thighs. These differences reflect the distinct hormonal influences on adipose tissue deposition.