Portal de Periódicos da CAPES

Secular Trends In Menarche

2005; Elsevier BV; Volume: 147; Issue: 6 Linguagem: Inglês

10.1016/j.jpeds.2005.08.065

1097-6833

Frank M. Biro,

Growth Hormone and Insulin-like Growth Factors

In this issue of The Journal, Anderson and Must1Anderson S.E. Must A. Interpreting the continued decline in the average age at menarche: results from two nationally representative surveys of US girls studied 10 years apart.J Pediatr. 2005; 147: 753-760Abstract Full Text Full Text PDF PubMed Scopus (181) Google Scholar compare the age of menarche in 2 nationally representative surveys of girls in the United States. The surveys, the National Health and Nutrition Examination Survey (NHANES) III and NHANES 1999-2002, were conducted roughly 10 years apart. The authors note that overall, the age of menarche declined by 0.19 years, from 12.53 to 12.34. However, when the analyses examined associations by race/ethnicity and relative weight (using age-specific body mass index [BMI] z-scores), the declines were much smaller. The authors recommend that when examining trends in age of menarche, one should consider changes in race/ethnicity distribution, as well as in relative weight. These results initially appear to be at variance with most other studies that have addressed this subject, including an article from the same authors comparing results of the National Health Examination Survey (NHES), conducted between 1963 and 1970, with those of NHANES III, conducted between 1988 and 1994.2Anderson S.E. Dallal G.E. Must A. Relative weight and race influence average age at menarche: results from two nationally representative surveys of US girls studied 25 years apart.Pediatrics. 2003; 111: 844-850Crossref PubMed Scopus (394) Google Scholar A recent article examined the consistencies and discrepancies between several studies, derived from U.S. data generated between 1963 and 1994.3Herman-Giddens M.E. Kaplowitz P.B. Wasserman R. Navigating the recent articles on girls' puberty in Pediatrics: what do we know and where do we go from here?.Pediatrics. 2004; : 911-917Crossref PubMed Scopus (99) Google Scholar Conclusions drawn from the comparisons included that girls are maturing earlier, with significant racial differences; there should be renewed efforts to collect nationally representative data regarding pubertal maturation; and further studies should examine the relationship between diet and environmental exposures to the onset of puberty.3Herman-Giddens M.E. Kaplowitz P.B. Wasserman R. Navigating the recent articles on girls' puberty in Pediatrics: what do we know and where do we go from here?.Pediatrics. 2004; : 911-917Crossref PubMed Scopus (99) Google Scholar Those articles raised several important issues above and beyond the interests of the researcher. These issues include whether real differences exist regarding earlier maturation or the data merely reflect differences in collection or analytic techniques, and what underlying etiologies may be driving the trend toward earlier maturation. The nationally representative studies are derived from large cross-sectional studies that implement complex probabilistic sampling techniques of the civilian noninstitutionalized population of the United States. In these studies, age of menarche is calculated from the proportion of girls who have attained menarche at the time of the survey (“status quo” method), with probit models constructed to generate the median age of the population. Given these constraints, however, some different conclusions about recent decreases in age of menarche can be drawn from the NHES and NHANES datasets.2Anderson S.E. Dallal G.E. Must A. Relative weight and race influence average age at menarche: results from two nationally representative surveys of US girls studied 25 years apart.Pediatrics. 2003; 111: 844-850Crossref PubMed Scopus (394) Google Scholar, 3Herman-Giddens M.E. Kaplowitz P.B. Wasserman R. Navigating the recent articles on girls' puberty in Pediatrics: what do we know and where do we go from here?.Pediatrics. 2004; : 911-917Crossref PubMed Scopus (99) Google Scholar, 4Chumlea W.C. Schubert C.M. Roche A.F. Kulin H.E. Lee P.A. Himes J.H. et al.Age at menarche and racial comparisons in US girls.Pediatrics. 2003; 111: 110-113Crossref PubMed Scopus (535) Google Scholar One could examine other recent studies that have focused on the temporal trend, using either longitudinal U.S. studies that are not nationally representative or studies from other societies. A comprehensive examination of these sources is beyond the scope of this editorial. However, an examination of several selected sources may prove informative. Several studies have provided longitudinal (or mixed-longitudinal) designs. An examination of secular trends in the Bogalusa Study reveals that age of menarche decreased by 9.5 months in black females and by 2 months among white females between 1973 and 1994, suggesting an interaction of environmental factors with racial and genetic factors.5Freedman D.S. Kettel Khan L. Serdula M.K. Dietz W.H. Srinivasan S.R. Berenson G.S. Relation of age at menarche to race, time period, and anthropometric dimensions: the Bogalusa Heart Study.Pediatrics. 2002; 110: e43Crossref PubMed Scopus (285) Google Scholar The Fels Longitudinal Study, which examined girls born in 6 10-year birth cohorts from the 1930s to the 1980s, found that the girls born in the 1980s experienced menarche 3 to 6 months earlier than those born in the 1930s; the correlation of age of menarche and birth year was small, but significant (r = −.14; P = .008).6Demerath E.W. Towne B. Chumlea W.C. Sun S.S. Czerwinski S.A. Remsberg K.E. et al.Recent decline in age at menarche: the Fels Longitudinal Study.Am J Hum Biol. 2004; 16: 453-457Crossref PubMed Scopus (116) Google Scholar The Bogalusa Study found a trend between increasing BMI and earlier maturation,7Wattigney W.A. Srinivasan S.R. Chen W. Greenlund K.J. Berenson G.S. Secular trend of earlier onset of menarche with increasing obesity in black and white girls: the Bogalusa Heart Study.Ethn Dis. 1999; 9: 181-189PubMed Google Scholar but the Fels Study did not.6Demerath E.W. Towne B. Chumlea W.C. Sun S.S. Czerwinski S.A. Remsberg K.E. et al.Recent decline in age at menarche: the Fels Longitudinal Study.Am J Hum Biol. 2004; 16: 453-457Crossref PubMed Scopus (116) Google Scholar Of note, many studies have noted an association between increased BMI and earlier onset of menarche.2Anderson S.E. Dallal G.E. Must A. Relative weight and race influence average age at menarche: results from two nationally representative surveys of US girls studied 25 years apart.Pediatrics. 2003; 111: 844-850Crossref PubMed Scopus (394) Google Scholar, 8De Ridder C.M. Thijssen J.H.H. Bruning P.F. van den Brande J.L. Zonderland M.L. Erich W.B.M. Body fat mass, body fat distribution, and pubertal development: a longitudinal study of physical and hormonal sexual maturation of girls.J Clin Endocrinol Metab. 1992; 75: 442-446Crossref PubMed Scopus (144) Google Scholar, 9Biro F.M. McMahon R.P. Striegel-Moore R. Crawford P.B. Obarzanek E. Morrison J.A. et al.Impact of timing of pubertal maturation on growth in black and white female adolescents: The National Heart, Lung, and Blood Institute Growth and Health Study.J Pediatr. 2001; 138: 636-643Abstract Full Text Full Text PDF PubMed Scopus (239) Google Scholar, 10Kaplowitz P.B. Slora E.J. Wasserman R.C. Pedlow S.E. Herman-Giddens M.E. Earlier onset of puberty in girls: relation to increased body mass index and race.Pediatrics. 2001; 108: 347-353Crossref PubMed Scopus (538) Google Scholar, 11De Muinck Keizer-Schrama S.M.P.F. Mul D. Trends in pubertal development in Europe.Hum Reprod Update. 2001; 7: 287-291Crossref PubMed Scopus (167) Google Scholar, 12Wang Y. Is obesity associated with early sexual maturation? A comparison of the association in American boys versus girls.Pediatrics. 2002; 110: 903-910Crossref PubMed Scopus (477) Google Scholar Wyshak and Frisch13Wyshak G. Frisch R.E. Evidence for a secular trend in age of menarche.N Engl J Med. 1982; 306: 1033-1035Crossref PubMed Scopus (353) Google Scholar noted a secular decrease in age of menarche through the 1970s. More recently, some European researchers have noted that although age of menarche has decreased over the last several decades, in the latest cohorts this decrease has declined to approximately 1 month or less,14Fredriks A.M. van Buuren S. Burgmeijer R.J.F. Meulmeester J.F. Beuker R.J. Brugman E. et al.Continuing positive secular growth change in the Netherlands, 1955-1997.Pediatr Res. 2000; 47: 316-323Crossref PubMed Scopus (917) Google Scholar and some studies have even reported modest increases in these cohorts.15Parent A.S. Teilmann G. Juul A. Skakkebaek N.E. Toppari J. Bourguignon J.P. The timing of normal puberty and the age limits of sexual precocity: variations around the world, secular trends, and changes after migration.Endocr Rev. 2003; 24: 668-693Crossref PubMed Scopus (1168) Google Scholar However, trends in Europe may reflect a decreased number of late maturers.12Wang Y. Is obesity associated with early sexual maturation? A comparison of the association in American boys versus girls.Pediatrics. 2002; 110: 903-910Crossref PubMed Scopus (477) Google Scholar The data presented by Anderson and Must1Anderson S.E. Must A. Interpreting the continued decline in the average age at menarche: results from two nationally representative surveys of US girls studied 10 years apart.J Pediatr. 2005; 147: 753-760Abstract Full Text Full Text PDF PubMed Scopus (181) Google Scholar are consistent, then, with the data published by our European colleagues and may prove to be a harbinger of future U.S. studies. Their findings could also reflect sampling strategies of the national studies, both with the use of cross-sectional designs and with sampling of other racial and ethnic groups, to accommodate population shifts within the United States. Increasing adiposity may have accounted in part for earlier reproductive potential. However, a threshold effect for critical adiposity may exist, as noted by Anderson and Must. In addition, interactions between environmental and genetic factors may be important, emphasizing the need for longitudinal studies to examine these issues.