PROS network study examines pubertal onset by race/ethnic groups [Pediatrics Classics Series]

Classics Series, Landmark Trials in Medicine

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1. In a study population of girls 3-12 years of age, it was found that African-American females developed secondary sexual characteristics at a significantly earlier age than white girls.

2. African-American females had earlier menarche at 12.16 years of age, compared to 12.88 years of age among white females.

Original Date of Publication: April 1997

Study Rundown: The onset of female pubertal changes varies greatly by race/ethnicity and setting. As the start of secondary characteristics marks a significant physiologic and psychological change in an individual’s life, being able to anticipate onset is essential to providing proper medical care. Prior to the initiation of this work, no nationally representative, racially diverse data was available to assess female pubertal status in the United States. This cross-sectional study stood as the first to investigate secondary sexual characteristics and menses onset among girls 3-12 years of age that could provide evidence representative of national norms. Researchers found that African-American girls developed secondary sexual characteristics including breast development, axillary hair, and pubic hair significantly earlier than white females, with all girls starting puberty six months to a year earlier than reported in prior studies. The average age of menarche in African-American females was 12.16 years of age compared to 12.88 years in white females. This study is limited by potential selection bias with non-random sample selection, the lack of hormone testing to provide a potential endocrinologic etiology for these developmental differences, and participants being heavier and taller, on average, than girls in the nationally-representative height and weight values provided by the Health and Nutrition Examination Surveys. Findings from this study indicated that the initiation of sex education and physician counseling should be tailored accordingly to earlier pubertal changes among girls.

Follow-up work to this initial paper was completed and published as documented below to dispel confusion regarding studies investigating this subject matter after 1997. One commentary further emphasized girls maturing earlier than previously documented with significant differences between race/ethnic groups persisting. In addition, the contribution of weight and other health characteristics to early pubertal onset is highlighted. Another, more recent publication supported these findings, indicating that thelarche onset differed by race/ethnicity and started earlier in those with higher BMI.

Click to read the study in Pediatrics

Click to read the follow-up commentary in Pediatrics

Click to read the follow-up study in Pediatrics

In-Depth [cross-sectional study]: In total, 17 077 female patients (90.4% white, 9.6% African American, ages 3-12 years old seen by one of 225 clinicians from 65 primary care offices across the country as part of the American Academy of Pediatrics Practice-based Research in the Office Settings (PROS) Network and who had a visit requiring a full physical exam were included in the study. The study was conducted from July 1992 to September 1993. Patients’ sexual maturity was staged by physicians trained and assessed in their ability to use Tanner staging criteria and a survey with questions regarding demographics, medical history, presence or absence of menses, and development of breast, pubic, and axillary hair was completed. Axillary hair was designated according to an original scale with stage 1 as no hair, stage 2 as sparse hair, and stage 3 as adult, mature hair. With and without controlling for height and weight, African American girls were found to develop secondary sexual characters significantly earlier than white girls (8.87 years v. 9.96 years for breast development, 8.78 years v. 10.51 years for pubic hair, and 10.01 v. 11.80 stage 2 axillary hair development; p < 0.001 for all findings). The average age of menses onset was 12.16 years for African American girls and 12.88 years for white girls. Significantly more African American females had menses by the age of 12 when compared to white girls (62.1% v. 35.2%, p < 0.001).

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