The monthly rhythm of incidence and age at menarche: thirty five years of research: The circa-vacation-study expectancy rhythm of incidence and age at menarche
Biol. Res
; 46(1): 21-26, 2013. tab
Article
em En
| LILACS
| ID: lil-676816
Biblioteca responsável:
CL1.1
ABSTRACT
The hypothesis that the vacation-study-expectancy scholar regime produces most of the monthly rhythm of the age at menarche (AaM) was tested. Studies on monthly menarche incidence (MI) refuted climatic factors as a main factor in this rhythm, and indicated that the main factor of this rhythm is the succession of expectancies of study (Stu-months) or vacation (Vac-months) months within a year. Thus the hypothesis of seasonal circa-annual rhythm should be modified to the circa-[vacation (fiesta)]-[study (non-fiesta)]-expectancies rhythm for the MI and age at menarche annual rhythms. In several countries Vac-months had higher MI than Stu-months. The high MI of Vac-months was followed by a large decrease when girls started their studies and a MI increase occurred as vacations approached. The hypothesis proposes that at the end of vacations and at the beginning of the study period the AaM should be lowest, and then the mean of AaM should increase because of the menarche delay of girls whose menarche was arrested by the initiation of school work. This pattern was found in four independent samples, from Chile, Colombia, USA and Brazil. The probability that this result be due to random fluctuation of means is extraordinarily low (P<10-8). I conclude that the influence of the expectancy of vacation and study periods on the monthly rhythm of the age at menarche is a real process that accounts for most of this rhythm.
Palavras-chave
Texto completo:
1
Índice:
LILACS
Assunto principal:
Periodicidade
/
Estudantes
/
Menarca
/
Menstruação
Tipo de estudo:
Incidence_studies
/
Prognostic_studies
/
Risk_factors_studies
Limite:
Female
/
Humans
País/Região como assunto:
America do norte
/
America do sul
/
Brasil
/
Chile
/
Colombia
Idioma:
En
Revista:
Biol. Res
Assunto da revista:
BIOLOGIA
Ano de publicação:
2013
Tipo de documento:
Article