Age at menarche and menstrual cycle pattern among school adolescent girls in China

Abstract

Objective To determine the age at menarche and patterns of menstruation among school girls in China. Methods With multi-stage sampling, 5 981 primary and middle school students from both urban and rural areas in eight provinces were investigated anonymously with the method of computer assisted self-interview (CASI). Results Menarche was attained at the age of (12.7±0.0) years, (12.4±0.0) years and (13.0±0.0) years for urban and rural respectively (P<0.01). The mean interval between menarche and regular cycle was (1.2±0.0) years. Analysis on the menstrual cycle pattern according to the time post menarche showed that the proportion of participants with regular cycle were similar in different time post menarche (P=0.33); the proportion of participants with blood flow duration between 4-7 d and moderate blood flow were increased with time (P<0.01); the incidence of dysmenorrhoea and degree of pain were increased with time (P<0.01). Conclusion The age of menarche of urban was 0.6 year earlier than that of rural. The proportion of participants with regular cycle was similar after 1 year postmenarche. The duration and amount of menstrual blood flow become the pattern of adult women with time. The incidence of dysmenorrhoea and severe pain increased with time. Key words: Menarche; Puberty development; Girls; Dysmenorrhoea