Deceleration of age at menarche in Poland.

The purpose of this paper is to describe secular growth changes in age at menarche of girls in Poland during the past 40 years. For this purpose data obtained from four consecutive surveys conducted in 1955, 1966, 1978 and 1988 were analysed. Each cohort was selected from settlements: big cities, small towns (approximately 10,000 inhabitants) and villages. Data regarding schoolgirls aged 7-18 years were collected by the status quo method. It was found that after the continuous trend towards an earlier maturation of Polish girls from 1955 to 1978 a substantial slowing down, and even a reverse trend, was observed. The deceleration of the age at menarche is most marked among girls from small towns. The results seem to have been caused by the retardation of menarcheal age in social groups which in the previous examinations were the earliest maturers.