Pubic hair is classified as terminal hair, meaning it is thick, coarse, heavily pigmented, and deeply rooted in the skin. This hair develops in the genital and groin region, primarily covering the mons pubis, the soft mound of tissue over the pubic bone. Before puberty, the area is covered only by fine, light vellus hair, often called “peach fuzz.” Pubic hair growth differs significantly from scalp hair, following a unique biological timetable. Understanding how pubic hair grows involves examining its specific shape, the cycle that governs its length, and the hormonal signals that initiate its appearance.
The Specific Shape of Pubic Hair Growth
The mature pattern of pubic hair growth is anatomically called the escutcheon, determined by genetics and sex hormones. This pattern develops into distinct shapes that vary between sexes due to the distribution of androgens during maturation. The typical female pattern is an inverted triangle, confined primarily to the pubic mound and labia.
The male pattern is often a diamond or rhomboid shape, extending upward from the pubic area toward the navel. Pubic hair is typically darker than scalp hair and has a coarse, often tightly curled or wavy texture. This texture results from the elliptical cross-section of the hair shaft, which causes it to curl as it grows.
The Phases of the Hair Growth Cycle
The length pubic hair reaches is regulated by the duration of its hair growth cycle, which consists of three phases.
Anagen Phase
The active growth phase, known as Anagen, is when cells in the hair bulb rapidly divide to form the hair shaft. For pubic hair, this phase is relatively short, lasting only a few months, which prevents the strands from growing long. Scalp hair, in contrast, has an Anagen phase that can last for several years.
Catagen Phase
Following active growth is the Catagen phase, a brief transitional period lasting approximately two to three weeks. During this time, the hair follicle shrinks, and growth ceases as the hair detaches from the blood supply.
Telogen Phase
The final stage is the Telogen phase, a resting period lasting around two to four months, where the hair remains anchored before being shed. Once the old hair is shed, the follicle re-enters the Anagen phase, and a new hair begins to grow, maintaining a short, cyclical pattern.
When Pubic Hair Starts to Appear
The emergence of pubic hair, called pubarche, is one of the earliest physical indicators of puberty. This development is triggered by the increase in androgens, sex hormones such as testosterone, produced by the adrenal glands and gonads. These rising hormone levels cause the fine, unpigmented vellus hair to transform into thick, pigmented terminal hair.
The initial appearance is subtle, starting as a few sparse hairs, often on the labia majora in females or at the base of the penis and scrotum in males. This initial stage is classified as Tanner Stage 2 of pubertal development. Over the next few years, the hair becomes progressively coarser, darker, and more abundant, spreading across the pubic region until the full adult pattern is achieved.