Pubarche
Pubarche refers to the first appearance of pubic hair at puberty. It is one of the earliest physical changes of puberty and can occur independently of complete puberty. It is usually the second sign of puberty, after thelarche in females and gonadarche in males.
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 with pubarche, defining it as the development of pubic hair that occurs at a mean age of 11.6 years in females and 12.6 years in males. 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.
Assessment
The Tanner scale remains the gold standard for determining pubarche. In clinical settings, this scale is primarily used by physicians, nurses, or other trained healthcare providers as part of a physical examination to assess the stage of puberty in children and adolescents, though in some cases the stage of puberty can be self-assessed.| Tanner stage | Description of pubic hair development |
| SMR 1 | Prepubertal – No pubic hair |
| SMR 2 | Pubarche – Sparse, fine, straight, downy hair over labia or penis |
| SMR 3 | Appearance of terminal hair – Adult quality, confined to the pubis |
| SMR 4 | Terminal hair fills the pubic region, not beyond inguinal crease |
| SMR 5 | Terminal hair extends onto medial thighs, achieving full adult distribution |
| SMR 6 | Terminal hair extends up the linea alba toward the umbilicus |
Average age
The average beginning of pubarche varies due to many factors, including environmental exposures, nourishment, weight, race and ethnicity, and geographical location. First pubic hair resulting from adrenarche may appear between ages of 10 and 12 at the beginning of puberty.Environmental exposures
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. 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. In everyday life, people are exposed to a various number of pesticides, with a large amount found to be disruptive to the endocrine system. Although dichlorodiphenyltrichloroethane and the metabolite dichlorodiphenyl dichloroethane were banned in the United States in the 1970s, countries around the world are still using these pesticides.Geographical location and nutritional needs
Geographical location and zones also plays a part in the timing of pubarche. A study was done in different zones in Nigeria and found that males in the Northeast, Northwest, and Southwest had an earlier timing of pubarche compared to the males in the Southeast, whereas females had delayed pubarche in the Southeast regions of Nigeria. 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 meet 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. The Dietary Guidelines for Americans 2010 declared that females between the ages of 9 and 13 years should meet a caloric intake of 1400 to 2200, while females between the ages of 14 and 18 years should meet a caloric intake of 1800 to 2400 calories a day.Premature 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, is the most common cause of premature pubarche. Premature pubarche is linked to adrenarcheal androgen levels with dehydroepiandrosterone sulfate 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 three 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 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.