[Secular trends in age at menarche in relation to body mass index].
OBJECTIVE
To evaluate the secular trend of menarche according to body mass index (BMI).


METHODS
Six hundred and eighty five girls (7-18 years) assessed in 2001 were compared with 750 evaluated in 2010. They were grouped by BMI Z-score: (thin + normal) and (overweight + obese). Menarche was reported by status quo and age at menarche estimated by a logit model. We used the Qui-square test, Mann-Whitney test, and Logistic Regression, at a 5% significance level.


RESULTS
Menarche advanced 3.24 months. There was an increase in obesity, and a decrease of the prevalence of normal girls. Menarche was anticipated by 1.44 month in the thin + normal group and by 5.76 months in the overweight + obese group. There was no interaction between the effects determined by the evaluated period and nutritional diagnosis.


CONCLUSIONS
Although both the period and BMI influence the menarche, one cannot attribute this advance only to changes in the nutritional profile of the sample. Other factors that were not tested may also contribute to this finding.
Faculdade de Medicina, Pontifícia Universidade Católica de Campinas (PUC-Campinas), Campinas, SP, Brasil. sdiezcast@puc-campinas.edu.br
Silvia Diez
SD
Castilho
Caroline Damasceno
CD
Pinheiro
Caroline Agnelli
CA
Bento
Antônio de Azevedo
Ade A
Barros-Filho
Monize
M
Cocetti
D000293:Adolescent; D000367:Age Factors; D017668:Age of Onset; D015992:Body Mass Index; D001938:Brazil / Q000453:epidemiology; D002648:Child; D005260:Female; D006801:Humans; D008572:Menarche / Q000502:physiology*; D009752:Nutritional Status / Q000502:physiology*; D009765:Obesity / Q000453:epidemiology*; D011157:Population Dynamics; D012741:Sexual Maturation / Q000502:physiology*; D012959:Socioeconomic Factors; D013851:Thinness / Q000175:diagnosis