Secular trend in age at menarche in China: a case study of two rural counties in Anhui Province

Abstract

There is increasing evidence that age at menarche has decreased in Europe and the United States during the last century and in Japan over the last several decades. Data from a community-based survey conducted in two rural counties of Anhui Province in China indicate a similar, downward secular trend in age at menarche for Chinese women. The present study shows the mean age at menarche decreased by 2.8 years, from 16.5 to 13.7, over an approximate 40-year time interval. This rapid decrease in age at menarche may partly be due to better nutrition and living standards reflected by the improved socioeconomic standards experienced in China over the past few decades. To test this hypothesis, a number of determinants of age at menarche were assessed; year of birth, literacy status, county of residence, amount of physical labour, general health status, pesticide exposure before age at menarche, and drinking water source were all found to be associated with age at menarche.

PIP: This study examined determinants of the mean age at menarche (MAM) in 2 rural counties (Zongyang and Huaining) of Anhui province, China. Data were obtained from a 1993 household community survey among about 12,727 Han women. Years of age were adjusted to account for the Chinese lunar calendar. Analysis pertains to 5-year birth cohorts during 1949-78 compared to all cohorts born before 1949. MAM declined from 16.5 years to 13.7 years over a 40-year period. The trend was linear. Year of birth and level of education were strongly related to a decrease in MAM. MAM was also significantly associated with county, physical labor, general health status, exposure to pesticides before age at menarche, and water source. Year of birth explained most of the difference in MAM. There were no significant interactions between birth year and literacy, water source, or pesticide exposure, or between county and amount of physical labor. Women from Zongyang county had a later MAM than women from Huaining. Illiterate women had a higher MAM than literate women. The decline in MAM is attributed to improved nutritional status and living standards since World War II. 788 women reported a MAM that was older than 19 years. Subtracting these women only resulted in a decrease in MAM to 15.9 years for the pre-1949 cohort. Findings suggest a similar MAM for Anhui province as for China as a whole.