Background: Several aspects of living conditions and behaviour may influence the age at menarche.
Aim: The present study investigated the relation of variables concerning the reproductive period and the socio-economic conditions on the recalled age at menarche of rural Portuguese women, born in the first half of the 20th century.
Subjects and method: Recalled menarche age of a sample of 771 adult women over 44 years old, from a rural municipality (Oleiros) in central Portugal was analysed.
Results: The mean menarcheal age was 14.34+/-1.98 years. Menarcheal age increased significantly with the chronological age and age at marriage, and was negatively correlated with the duration of the period between menarche and marriage and with the biological reproductive span. The mean menarcheal age was lower (13.59+/-1.95 years) in women with an order of birth >/=7 than in those of birth order </=3 (14.41+/-2.16 years). The mean menarcheal age was lower in women with a surname (14.26+/-1.91) than in those without it (14.81+/-2.28). Child labour began at the age of 11.87+/-32.72 years. Women subject to early child labour had delayed menarches (14.53+/-2.18) when compared with women who had not worked before 17 years old (14.03+/-1.91). The menarcheal age varied with the birth decade, decreasing from 14.64+/-2.61 (1910s) to 13.98+/-1.46 (1950s).
Conclusion: The variation of age at menarche was related to changes in family behaviour towards children, reduction of age at child labour and increasing access to schools. The secular decrease in menarcheal age from 1910 to 1980 was related to living condition factors such as illiteracy, female life expectancy and infant mortality rates.