Family socio-economic background modified secular trends in age at menarche: evidence from the Pro-Saude Study (Rio de Janeiro, Brazil).
Junqueira Do Lago M, Faerstein E, De Souza Lopes C, Werneck GL; Pro-Saude Study (Rio de Janeiro, Brazil)
Ann Hum Biol. 2003 May-Jun;30(3):347-52
BACKGROUND: Since age at menarche has been associated with socio-economic status, its downward secular trend might vary according to the different socio-economic status levels of the family in which women lived during their childhood. AIM: This study seeks to describe secular trends in age at menarche for Brazilian women whose fathers had different levels of educational attainment. SUBJECTS AND METHODS: A self-administered questionnaire was applied to 2053 women born between 1931 and 1977. Multiple linear regression models were employed to estimate trends in age at menarche according to categories of educational level of the participants' father. RESULTS: The age at first menstruation varied from 7 to 19 years, with a mean age of 12.3 years (+/- 1.64 SD). The reduction in age at menarche was 2.4 months per decade for all women. Among daughters of fathers with less than 8 years of schooling this reduction was 3.6 months per decade, and among daughters of fathers with 8 years or more of study it was 1.2 months per decade. CONCLUSION: Improvements in living conditions in Brazil over the last decades seem to have had a stronger effect on the reduction of the age at menarche among women who lived their childhood in worse socio-economic standards.
The aggregate data (with a mean reduction of 2.4 months per decade) reveal little difference from the 1 year per 45 years for the developed world, the faster rate for poorer families (3.6 months per decade, which is nearer 1.5 years per 45, could be significant. It depends.