PEDIATRICS Vol. 107 No. 6 June 2001, pp. 1493

Age of Puberty Among Girls and the Diagnosis of Precocious Puberty

To the Editor.

There continues to be considerable lay and professional interest^1,2 in the data discussed by Kaplowitz and Oberfield³ which began with a 1997 publication,⁴ presenting data from a study cohort of >17 000 girls indicating that puberty among females begins earlier than previously thought. The cause of such putative changes includes continuation of secular trends toward earlier puberty since 1900, obesity, "endocrine disruptors," or other factors. Furthermore, it has raised questions about the age-based definition of the diagnosis and the treatment of precocious puberty.

To explore the best available data, comparisons should be made with data from the National Health Examination Surveys (NHES) from 1963 to 1970 (mostly unpublished except pubertal staging from cycle III of this survey⁵) and the National Health and Nutrition Examination Survey (NHANES III) (mostly as yet unpublished) collected between 1988 and 1994. These are the only other large studies available for comparison with the Pediatric Research in Office Settings (PROS) data⁴ collected in 1992 and 1993. We have summarized data from the PROS study using weighted means based on the percentage of the population at each age who were white and black. Data from the NHES (n = 6150 for age of menarche and 3185 for stages of puberty) and NHANES III (n = 3197) surveys are summarized without correcting for differences between racial representation in the study and in the population during the years of sampling.

These summaries, published elsewhere, compare informative data from these 3 surveys, even though the ages assessed vary. Concerning the onset of Tanner 2 breast development, the NHANES data for ages 8 through 12 virtually overlap the PROS data when expressed as percentages for the entire population (Fig 1). Both indicate that 12% to 14% of females have Tanner 2 breast development or greater while 8 years of age. The median age for the attainment of Tanner 2 breast development is 9.5 years from PROS and 9.7 years for NHANES. Both of these indicate that the median age of onset of pubertal breast development is younger than previously thought, prior reports from small studies indicating that the mean age for onset was 10.5 to 11.3 years with the early limit, presumed to approximate2 SD, at 8 years.^6,7 Although inadequate comparison data do not allow verification of change, puberty among females appears to begin earlier than previously thought.

View larger version (26K): [in this window] [in a new window]   Fig. 1.   Data concerning onset of breast development, menarche and pubertal completion from 3 large studies (PROS, NHES, and NHANES) of pubertal age. Adapted from Lee PA, Guo SS, Kulin HE. Age of puberty: data from the United States of America. Acta Pathol Microbiol et Immunol Scand. In press. Used with the permission of the authors.

Even if onset is earlier, these same data sources did not find that the age of menarche has changed. The median age of menarche, while 12 years old, is the same for the NHES, NHANES III, and PROS data (Fig. 1). Furthermore, the age of attainment of Tanner 5 breast development is not different when the percentages for age are compared between the NHES and NHANES III data from 12 through 17 years, the 50th percentile being at age 14 years (Fig 1).

Thus, although these data suggest that puberty is beginning earlier than previously thought, it is not being completed earlier nor is menarche occurring earlier. Puberty among those with early onset may be progressing at a slower pace, or the initial appearance of breast growth may not herald the real onset of puberty. The earlier onset may be attributable to a different ethnic mix or a shift within minority groups, influencing the overall data.

The impact on the diagnosis of precocious puberty involves the requirement of criteria more than a simple age limit. All puberty that appears to begin with breast development when a girl is age 6 or 7 is not precocious puberty. Only puberty that progresses inappropriately so that growth and developmental characteristics are clearly excessive for age with diminished growth potential should be considered for therapy to suppress pubertal development.

Peter A. Lee, MD, PhD
Howard E. Kulin, MD
Department of Pediatrics
Penn State University College of Medicine
Milton S. Hershey Medical Center
Hershey, PA 17033-0850

Shumei S. Guo, PhD
Department of Community Health
Wright State University School of Medicine
Kettering, OH 45420

REFERENCES

1. Kolata G. Doubters fault theory finding earlier puberty. New York Times. February 20, 2001:A1, A6
2. Rosenfield RL, Bachrach LK, Chernausek SD, Current age of onset of puberty. Pediatrics. 2000; 106:622-623 [Free Full Text]
3. Kaplowitz PB, Oberfield SE Reexamination of the age limit for defining when puberty is precocious in girls in the United States: implications for evaluation and treatment. Pediatrics. 1999; 104:936-941 [Abstract/Free Full Text]
4. Herman-Giddens ME, Slora EJ, Wasserman RC, Secondary sexual characteristics and menses in young girls seen in office practice: a study from the Pediatric Research in Office Settings network. Pediatrics. 1997; 99:505-512 [Abstract/Free Full Text]
5. Harlan WR, Harlan EA, Grillo GP Secondary sex characteristics of girls 12 to 17 years of age. The US Health Examination Survey. J Pediatr. 1980; 96:1074-1078 [CrossRef][Medline]
6. Lee PA Normal ages of pubertal events among American males and females. J Adolesc Health Care. 1980; 1:26-29 [CrossRef][Medline]
7. Roche AF, Wellens R, Attie KM, Siervogel RM The timing of sexual maturation in a group of US white youths. J Pediatr Endocrinol Metab. 1995; 8:11-18 [Medline]