Menarcheal age and socio-economic factors in Poland.
Menarcheal age is the most important measure of sexual maturation in girls and a sensitive indicator of environmental conditions during childhood. The study analysed the association between age at menarche and socio-economic characteristics (urbanization, population size, education of parents and number of children in the family). Questionnaire data were collected from 3271 female schoolchildren born between 1981 and 1984, living in three provinces of southern Poland. Menarcheal age was estimated by the recall method and based on the date of menarche given by the study participants. ANCOVA and multiple regression analyses were applied to test statistical significance of differences between groups. Girls from families with high socio-economic status experience menarche at an earlier age than girls from families with lower socio-economic status. However, depending on the geographical region and the population size, other factors influence menarcheal age. In the Krakow province, factors that significantly differentiate age at menarche are urbanization, father's education and number of children in the family; in the Opole province, these factors include urbanization and number of children in the family, while in the Nowy Sacz province, number of children in the family is significant. Socio-economic differences are greater in a large urban city (Krakow), and affect variation in age at menarche. However, within smaller populations (Opole, Nowy Sacz) living in towns and villages, the difference in age at menarche is less visible. In addition, variation between areas reveals a lower age at menarche in urban as compared with non-urban areas.