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Debut of pubic hair following the onset of puberty
Pubarche ('/p//j//uː/,/b//ɑɹ//k//i/) refers to the first appearance of pubic hair at puberty and it also marks the beginning of puberty. It is one of the physical changes of puberty and can occur independently of complete puberty. The early stage of sexual maturation, also known as adrenarche, is marked by characteristics including the development of pubic hair, axillary hair, adult apocrine body odor, acne, and increased oiliness of hair and skin. The Encyclopedia of Child and Adolescent Health corresponds SMR2 (sexual maturity rating) with pubarche, defining it as the development of pubic hair that occurs at a mean age of 11.6 years in females (range 9.3–13.9 years) and 12.6 years in males (range 10.7–14.5 years). It further describes that pubarche's physical manifestation is vellus hair over the labia or the base of the penis. See Table 1 for the entirety of the sexual maturity rating description. A study researched whether thelarche pathway, beginning puberty with breast development alone, or the pubarche pathway, beginning puberty with pubic hair development alone, represents the true pubertal development. The study is an observational, longitudinal cohort study. The study cohort is limited to a group of black and white girls who were seen annually for ten years. It is concluded in the research that pubarche may represent true pubertal maturation.

The average beginning of pubarche varies due to many factors, including environmental exposures, nourishment, weight, race and ethnicity, and geographical location. First (and often transient) pubic hair resulting from adrenarche may appear between ages 10–12 at the beginning of puberty.

Chemical toxins in the environment are one of many factors influencing adolescent development. In the early 1970s, more than 4000 people were accidentally exposed to polybrominated biphenyls (PBBs). A study was conducted in the child bearing women exposed to the toxin, with their baby girls reaching menarche by the age of 11.6 years, compared to girls who had low exposure reaching menarche by the age of 12.2–12.6 years. Within these regions, socio economic classes were also taken into consideration. They found that households with a higher economic status posed an increased risk of premature, or an early onset of pubarche, possibly related to food being easily accessible. Nutrition is vital in adolescent development. Failure to meeting average nutritional needs, such as calcium and vitamin D for bone growth, may result in growth stunting. Over nourishment and/or living a sedentary lifestyle can lead to obesity which can also affect adolescent pubarche.

Premature pubarche, or precocious pubarche, refers to the appearance of pubic hair before the age of 8 in females or before the age of 9 in males. Premature pubarche is one marker of "incomplete, partial, or dissociated precocious puberty", where incomplete puberty refers to the premature development of one secondary sexual characteristic, such as premature thelarche or premature pubarche. Premature adrenarche, as indicated by elevated levels of steroids that are naturally produced by the body (e. g., DHEAS), is the most common cause of premature pubarche. Premature pubarche is linked to adrenarcheal androgen levels with dehydroepiandrosterone sulfate (DHEAS) of 40–130 ųg/dL. However, premature pubarche may also arise independently of adrenarche. Premature pubarche is a subset of precocious puberty which divide into 1) true precocious puberty that includes complete and central precocious puberty and 2) incomplete puberty which has 3 subsets: premature thelacrche, premature pubarche and isolated menarche. When adrenarche, an increase in adrenal androgen production, central puberty, and all disease causing conditions have been excluded, the term isolated premature pubarche is used to describe the unexplained development of pubic hair at an early age in people without other hormonal or physical changes of puberty. Other potential indicators of premature puberty should also be considered when diagonosing premature pubarche, such as hyperandrogenemia (high levels of androgen in the blood) and virilization. Premature pubarche is also a symptom of other hormone and puberty related medical conditions, including polycystic ovary syndrome, and classic and non classic congenital adrenal hyperplasia.

When premature pubarche has been identified, the clinical examination primarily involves the assessment of signs indicating an elevation of androgens in the body, as well as overall body growth and bone age. If these factors appear normal, it is considered "simple premature pubarche", and it is recommended to monitor its progression to distinguish between central precious puberty or adolescent polycystic ovary syndrome. If these factors, especially body growth and bone age, appear to increase faster than usual, tests for various hormones may be ordered. These tests may include testosterone, 17 OH, DHEAS, and Synacthen test.

Scientists have traditionally thought that premature pubarche has no significant effect to the body, and this is reflected in the lack of a scientific consensus with respect to treatment of premature pubarche. However, it has now been shown clinically that it could be a forerunner of the metabolic syndrome, a cause clinical ovarian androgen excess and hyperinsulinemia in adolescence. Studies have shown that females with premature pubarche and lower birth weight obtained reduced height as adults because of early onset of puberty and a shorter duration of puberty. There is ongoing study on metformin therapy in these females with the goal to improve final height. The use of metformin has been shown clinically to prevent ovarian hyperandrogenism development in females with premature pubarche. A randomized control trial studied the effect of metformin 850 mg daily for 12 months compared to placebo. The results show that all abnormalities regarding insulini sensitivity, serum androgens, lipids, total and truncal fat mass, and lean body mass were reversed within 6 months. The untreated group had data that continued to deviate from the normal range. Later on, a cohort study replicated these results. In young females, the development of breasts and pubic hair can occur at different times. Some may experience breast development before the start of pubic hair growth, and vice versa. Therefore, in order to determine if delayed pubarche is a health issue or not, looking for the signs of puberty happening and the specific timing of it is important to note. The determination of the underlying cause of delayed pubarche can be done so with specific tests of antibodies, karyotype, and hormone levels (i. e., cortisol, thyroid stimulating hormone).

Adrenal insufficiency is a life threatening medical condition in which the adrenal gland is damaged. This leads to not enough hormones being produced, which include glucocorticoids and mineralcorticoids. These types of hormones are crucial for the regulation of many functions in the body and with not enough levels of these hormones that are produced by the adrenal glands, it can lead to primary adrenal insufficiency. Delayed pubarche can be expected in young individuals with this medical condition due to the lack of hormones that aid for pubic hair growth. Therefore, if signs and symptoms of adrenal insufficiency are present such as fatigue, weakness, abdominal pain, or any history an autoimmune disease, adrenal insufficiency should be taken into consideration as an underlying cause for delayed pubarche.