The menarcheal age of Chinese girls

The menarcheal age of Chinese girls was analysed based on a national survey in 1985. A total of 162,902 girls, aged 7–22 years, of Han nationality and 34,232 girls, aged 7–18, of 27 minority nationalities were sampled. Data were further subdivided into urban and rural areas. It was found that the curves of menstruating percentage in each of the subgroup were in long sigmoid shapes. The menstruating rate (MR) of Han girls was higher than that of the minority girls in almost every age group. The median menarcheal age (MMA) of Han girls was significantly lower than that of the minority girls. In Han nationality the urban girls showed higher MR and lower MMA than the rural girls. The influence of hereditary, cultural and economical factors on menarcheal age in Chinese girls is discussed. The data of this study were also compared with research reports from other world literature.     

The menarcheal age of Chinese girls.

The menarcheal age of Chinese girls was analysed based on a national survey in 1985. A total of 162,902 girls, aged 7-22 years, of Han nationality and 34,232 girls, aged 7-18, of 27 minority nationalities were sampled. Data were further subdivided into urban and rural areas. It was found that the curves of menstruating percentage in each of the subgroup were in long sigmoid shapes. The menstruating rate (MR) of Han girls was higher than that of the minority girls in almost every age group. The median menarcheal age (MMA) of Han girls was significantly lower than that of the minority girls. In Han nationality the urban girls showed higher MR and lower MMA than the rural girls. The influence of hereditary, cultural and economical factors on menarcheal age in Chinese girls is discussed. The data of this study were also compared with research reports from other world literature.     

The relation of menarcheal age to anthropometric profiles in Korean girls

The aim of this study was to represent the trend of early menarche and to assess the association of age at menarche with anthropometric profiles of Korean children and adolescents. A cross sectional survey was conducted with 13,371 girls aged 10 to 18 yr, recruited nationwide from April, 2005 to March, 2006. Height, weight and waist circumference of the subjects were measured; and the subjects self-reported their ages at menarche. We found that the menarcheal girls were taller (P<0.05 for the girls between 10 and 14 yr) and heavier (P<0.05 for the girls between 10 and 18 yr) than non-menarcheal ones. Menarcheal girls also showed higher body mass index (BMI), and greater waist circumference than non-menarcheal ones. Significant differences were represented according to the age at menarche in terms of BMI, waist circumference, % body fat mass, waist hip ratio and neck circumference as well as height and weight (P<0.05). In conclusion, girls who matured early were taller and heavier in early adolescence than those who matured later.     

Height, weight and menarcheal age of adolescent girls in Oman

A cross-sectional survey was carried out on 683 school girls aged 11.5-18.5 years in Oman, in order to assess their physical growth. Height, weight and age at menarche were measured. Results showed that median height and weight of Omani girls fluctuates between 25th and 5th percentiles and 25th and 10th percentiles of the North American reference standard (NCHS), respectively. The mean age at menarche was 13.3 +/- 0.09 years. In general Omani girls are shorter and lighter than girls of similar age in other Arabian Gulf countries (Bahrain and Kuwait).     

Mother-daughter differences in menarcheal age in adolescent girls attending national dance company schools and non-dancers

A combination of genetic and environmental factors is thought to contribute to age of menarche. Adolescent athletes and dancers are much more likely to have a delayed menarche than are non-athletes. To examine the possible differential influence of heredity and environmental factors on menarcheal age, 350 adolescent dancers and non-dancers and their mothers were surveyed. The dancers had a later age of menarche than did the comparison group; their mothers did not differ with respect to menarcheal age, suggesting that delayed menarche in athletes is not solely due to genetic selection as inferred by maternal menarcheal age. Maternal menarcheal age was the best predictor of menarcheal age in the comparison sample, while leanness was in the dance sample.     

Social-class gradients in menarcheal age in Poland

In a sample of approx. 19 000 Polish schoolgirls from the three largest cities of the Upper Silesia conurbation, menarcheal age was studied in relation to parental education (four levels) and father's occupation (12 groups). Menarcheal age tends to increase with decreasing parental education, although the gradient is not steep. When families below a certain level of economic standing are discarded from the best-educated and the least-well-educated groups, mean menarcheal age, surprisingly, decreases much more in the former than in the latter. Mean menarcheal ages for girls from different occupational groups range from 12.82 to 13.30 years and form the following sequence, in increasing order: managers--police--non-technical professionals--engineers, technicians and foremen--skilled industrial workers and small businessmen--unskilled workers--coal-miners. Mean menarcheal age for an occupational group is strongly dependent upon the group's socio-economic status, the latter being defined in terms of parental education, family income, family size, and dwelling conditions. However, daughters of men in the police force mature significantly earlier, and daughters of coal-miners significantly later, than would be expected from each group's rank in socio-economic status. The findings are compared with the results of other recent studies of social gradients in menarcheal age in Poland.     

Social conditions and menarcheal age: the importance of early years of life

Data on the historical trends for menarcheal age and socio-economic conditions in Norway are used to investigate whether the reproductive system in humans is especially sensitive to environmental stimuli during any particular short age periods. The method which has been used is based on the irregularity in the trend for socio-economic development. These irregularities are reflected in the Gross Domestic Product (GDP), a quantity for which official estimates are available from 1865 onwards. Estimates of menarcheal age for women born in each year from about 1840 have been calculated from information obtained from maternity clinic records.

For the period between 1900 and World War II, a close correspondence is found between the GDP in a year, and the menarcheal age of women born in the same or the preceding year. For the years before 1900, the data on menarcheal age is less satisfactory, but the correspondence may be fairly good also for this period. When values of GDP corresponding to higher ages is used, the correlation is less satisfactory. Other information on the susceptibility of the reproductive system towards environmental influences is reviewed. The following conclusion is reached: during the period around or after birth, the processes leading to menarche are clearly more sensitive than at later ages. During adolescence, the maturation process may be influenced somewhat, but probably not much as long as the conditions are not adverse. These observations may be seen as illustrating that phenomena corresponding to the critical or sensitive periods described for animal species, are also observable during the longer-lasting process of human development.     

A study of menarcheal age in India

A study of menarcheal age was carried out in southern India. A logit method of analysis was applied to status quo data on 1267 Tamil and Telugu speaking girls aged 9 to 18 years in 3 schools catering for different socio-economic groups. There appears to be no relationship of menarcheal age with dietary pattern classified simply as vegetarian and non-vegetarian. Differences in median age at menarche between schools correspond well with the socio-economic differences between them. The median age in the most advantaged school (12·86 years) is comparable with that in recent studies in southern and eastern Europe, and may perhaps be in advance of some recent north-west European samples.     

A continuous decline in menarcheal age in Denmark

We report a renewed decline in mean menarcheal age in a large Danish sample after a period with a halt in the trend towards earlier age at menarche in many North European countries. In our study based on retrospective data from six different samples constituting 42784 women, we find a continuously declining mean menarcheal age in Denmark among women born in the years 1964-1973. In a sample of textile workers born in the years 1939-1968 (n = 12605) we find a 1 year higher mean menarcheal age. This indicates that menarcheal age is still delayed in certain groups in Denmark. This leaves the possibility that the menarcheal age could fall even further in the future.     

A continuous decline in menarcheal age in Denmark

We report a renewed decline in mean menarcheal age in a large Danish sample after a period with a halt in the trend towards earlier age at menarche in many North European countries. In our study based on retrospective data from six different samples constituting 42784 women, we find a continuously declining mean menarcheal age in Denmark among women born in the years 1964-1973. In a sample of textile workers born in the years 1939-1968 (n = 12605) we find a 1 year higher mean menarcheal age. This indicates that menarcheal age is still delayed in certain groups in Denmark. This leaves the possibility that the menarcheal age could fall even further in the future.     

Changes of recollected menarcheal age and month among women in Tokyo over a period of 90 years

Data on the recollected age at menarche of 47,881 women born between 1881 and 1970 were examined. The mean menarcheal age had changed from 15.1 years in those born up to 1900 to 12.5 years in those born during the 1960s. The age at menarche differed according to the month of birth, and the pattern of average age distribution by month of birth was not the same when the year of birth was different. Among women born before 1955 the menarcheal age was earlier in those born in the summer. However, among women born after 1955, menarche occurred later when they were born in the summer. The monthly distribution of menarche had also changed during this 90-year period. Two peaks in April and August were prominent among those born up to 1960. A third peak in January became also apparent in those born after 1960.     

Family composition and menarcheal age: anti-inbreeding strategies.

Family composition (e.g., the absence of a father) is associated with pubertal timing in women, although the socioendocrinology of the human primate is poorly understood. To better understand social influences on sexual maturation, retrospective data were collected on menarcheal age and family composition from a sample of approximately 1,938 participants from a college population. Absence of a biological father, the presence of half- and step-brothers, and living in an urban environment were associated with earlier menarche. The presence of sisters in the household while growing up, especially older sisters, was associated with delayed menarche. Menarcheal age was not affected by number of brothers in the household, nor was there an effect of birth order. Body weight and race were also associated with menarche. The present findings advance the literature as they are suggestive of putative human pheromones that modulate sexual maturation to promote gene survival and prevent inbreeding, as occurs in rodents and nonhuman primates.     

Influence of family size and birth order on menarcheal age of girls from Bilbao city (Biscay,Basque country)

From a sample of 895 girls from Bilbao 9.5 to 18.5 years of age, the possible influence of family size and birth order on menarcheal age was analyzed. The earliest mean ages of menarche occurred in girls from families of one or four or more children, or who occupied the first or last birth order in their families. Later mean ages of menarche occurred in girls belonging to sibships with two or three children or who occupied the second or third birth order in their families, the latest being girls belonging to sibships of three children or of third birth order. This may be due to the variations in the interval of time between births, leading to better care and less stress for the youngest individual of the family and, hence, may be indicative of psychological as well as biological factors affecting maturation. Am. J. Hum. Biol. 11:779–783, 1999. © 1999 Wiley-Liss, Inc.     

Genetic correlates of menarcheal age: a multivariate twin study

Multivariate genetic models were fitted to data from 44 pairs of MZ and 42 pairs of DZ twin girls on weight, height, and skeletal maturation at the age of menarche, in order to obtain information on genetic relationships of those measures with the age of menarche. The relationships of all three physical measures with this age were largely genetically controlled, but a genetic system controlling skeletal maturity was identified as the only genetic determinant of menarcheal age, independent of those systems of the two remaining physical measures. Heritabilities of all individual traits considered in the study were uniformly high. Possible links of genetic information with hormonal functions determining menarche are discussed.     

Trend in menarcheal age in Spain: rural and urban comparison during a recent period

Menarcheal age of a sample of rural (n = 342) and urban (n = 469) girls with ages ranging from 9 to 16 years from Madrid province was analysed. Results, obtained through the status quo method and probit analysis (age 12.79 SD 1.04 in Madrid city and 12.90 SD 1.03 in rural sample), were compared with data from previous studies carried out in the same area, as well as those from other regions of the Iberian Peninsula. The aim of these comparisons was to establish the variability of menarche in the recent past, considering physical environment, degree of urbanization and socio-economic development. Decline in menarcheal age was detected and, in general, a tendency towards similar means among Spanish populations in the period studied.     

Measures of genotoxicity in Gulf war I veterans exposed to depleted uranium

Exposure to depleted uranium (DU), an alpha‐emitting heavy metal, has prompted the inclusion of markers of genotoxicity in the long‐term medical surveillance of a cohort of DU‐exposed Gulf War veterans followed since 1994. Using urine U (uU) concentration as the measure of U body burden, the cohort has been stratified into low‐u (<0.10 μg U/g creatinine) and high‐u groups (≥0.10 μg U/g creatinine). Surveillance outcomes for this cohort have historically included markers of mutagenicity and clastogenicity, with past results showing generally nonsignificant differences between low‐ vs. high‐U groups. However, mean hypoxanthine‐guanine phosphoribosyl transferase (HPRT) mutant frequencies (MFs) have been almost 50% higher in the high‐U group. We report here results of a more comprehensive protocol performed in a 2009 evaluation of a subgroup (N = 35) of this cohort. Four biomarkers of genotoxicity [micronuclei (MN), chromosome aberrations, and MFs of HPRT and PIGA] were examined. There were no statistically significant differences in any outcome measure when results were compared between the low‐ vs. high‐U groups. However, modeling of the HPRT MF results suggests a possible threshold effect for MFs occurring in the highest U exposed cohort members. Mutational spectral analysis of HPRT mutations is underway to clarify a potential clonal vs. a threshold uU effect to explain this observation. This study provides a comprehensive evaluation of a human population chronically exposed to DU and demonstrates a relatively weak genotoxic effect of the DU exposure. These results may explain the lack of clear epidemiologic evidence for U carcinogenicity in humans. Environ. Mol. Mutagen., 2011. © 2011 Wiley‐Liss, Inc.     

The reliability of recalled estimates of menarcheal age in a sample of older women

The accuracy of recalled age at first menses has been questioned, particularly if subjects are relatively old. This paper illustrates the use of a statistical technique that quantifies the reliability of recalled age at menarche based on re-interview of a small (15–20) subsample of subjects. Menarcheal age collected with the retrospective method in a sample of 108 females, 50 years of age and older, from Limón, Costa Rica, is reliable.     

月经初潮年龄对壮族女大学生体型分布的影响

目的　探讨月经初潮年龄对女大学生体型分布的影响。方法　对 10 3名 2 0岁壮族女大学生的月经初潮年龄进行调查研究 ,并作Heath Carter体型分析。结果　得出 4个不同月经初潮年龄组的体型均值和 10 3名 2 0名壮族女大学生的体型均值 ,表明均为三胚中间型体型。结论　壮族女大学生的体型不受月经初潮年龄的影响。     

The age of menarche in Irish girls

Age at menarche in Ireland is analyzed using data from a representative sample of 2,940 girls aged 9 to 17 drawn from schools in Dublin, Dundalk, Navan, and Portlaoise, of whom some half were urban and half rural residents. The mean age at menarche was 13.52 years. The authors note that this is the latest mean age at menarche recorded for a contemporary European population. No significant differences in age at menarche by place of residence or social class were noted.