Secular trends in average height and age at menarche of ethnic Russians and Komi-Permyaks of the Permsky Krai, Russia

The aim was to describe the changes in body size and age at menarche in anthropologically distinct ethnic groups Komi-Permyaks (KP) and Russians (RU) of Permsky Krai that occurred in the last century, with a special concern to the urban-rural differences. The comparison of the 1861-1865 and 1990 birth cohorts (BiCo) revealed following results. In RU rural males the increase in stature (ST) was 10.8 cm (p < 0.001). The chest circumference has increased by 5.9 cm, but it is unsubstantial 0.25 % when measured in relative to ST values. In RU urban males the overall increase in ST was 10.8 cm (p < 0.001), chest circumference increased by 10.5 cm. The peak increase in ST (+1.36 cm per decade) was attained between the 1964 and the 1990 BiCo. The data on body dimensions of RU females available only from the 1960s to 1990. The ST of rural females has not changed, but the absolute and the relative (to ST) values of pelvic width of the 1980-1989 BiCo are significantly (p <0.05) lower than in the 1966-1975 and 1965 BiCo. The RU urban females of the 1985 BiCo are 3.6 cm taller than 1964 BiCo (p < 0.001), but over the next 5 years the ST decreased by 2 cm (p = 0.06). The relative pelvic width has decreased from 17.57% (BiCo 1965-1969) to 17.18% (BiCo 1980-1989; p < 0.05). Menarcheal age of Perm females declined from 14.5 yrs in the 1930-1939 BiCo to 13.3 yrs in 1950-1965 BiCo, then ceased to change. The changes across generations in rural KP were weak. The rural males born in 1885 were 2.1 cm taller than BiCo 1861-1865. From the 1925 to 1975 BiCo the average ST increased by 6.2 cm (1.24 cm/decade). KP rural females became 6.4 cm taller from the 1885 to 1985 BiCo. Pelvic width in the 1985 BiCo (27.4 cm) is significantly bigger (p < 0.05) than in the 1975 BiCo (26.9 cm). The changes in ST of urban KP females were more obvious than in rural groups. The 1985 BiCo of urban KP females (ST 161.8 cm) are taller than those born in 1965 (159.4 cm; p < 0.05), but their pelvic width does not differ. In urban and rural KP females age at menarche is earlier in the 1976-1985 than in the 1966-1975 BiCo (p < 0.01). In all the KP cohorts, urban females have earlier menarche than rural (p < 0.05).