Menarcheal age and socio-economic factors in Poland

Background:?Menarcheal age is the most important measure of sexual maturation in girls and a sensitive indicator of environmental conditions during childhood.

Objective:?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).

Subjects and methods:?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.

Results:?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.

Conclusions:?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.

Résumé. Arrière plan: L’âge aux premières règles est une mesure importante de la maturation sexuelle des filles ainsi qu’un indicateur sensible des conditions du milieu au cours de l’enfance.

Objectif: Cette étude analyse l’association entre âge aux premières règles et facteurs socio-économiques (urbanisation, taille de la population, éducation parentale et nombre d’enfants dans la famille).

Sujets et méthodes: Des données par questionnaire ont été rassemblées sur 3271 écoliers habitant dans trois provinces du sud de la Pologne, nés entre 1981 et 1984. L’âge aux premières règles a été estimé par la méthode de mémorisation. Des analyses de régression multiple et de covariance (ANCOVA) ont été effectuées afin d’évaluer la signification statistique des différences entre groupes.

Résultats: Les filles de familles à statut socio-économique élevé sont plus précoces que celles de statut socio-économique défavorable, mais suivant la région et la dimension de la population, d’autres facteurs influencent l’âge aux premières règles. Dans la province de Cracovie, l’urbanisation, l’éducation du père et le nombre d’enfants dans la famille jouent un rôle significatif. Dans la province d’Opole, ce sont l’urbanisation, l’éducation du père et le nombre d’enfants dans la famille qui interviennent, alors que dans la province de Nowi Sacz, est significatif le nombre d’enfants dans la famille.

Conclusions: Les différences socio-économiques sont plus significatives dans une grande ville (Cracovie), alors que dans les ensembles populationnels plus restreints (Opole, Nowy Sacz), elles sont de moindre importance. Par ailleurs, la variation entre régions révèle un âge aux premières règles plus précoce chez les filles urbaines que chez les rurales.

Zusammenfassung. Hintergrund: Das Menarchealter ist das wichtigste Maß für die sexuelle Reife bei Mädchen und ein empfindlicher Indikator für Umweltbedingungen während der Kindheit.

Ziel: Die Studie analysierte die Beziehung zwischen Menarchealter und sozio-ökonomischen Kennzeichen (Urbanisation, Populationsgröße, Schulbildung der Eltern und Anzahl der Kinder pro Familie).

Probanden und Methoden: Mittels Fragebögen wurden Daten von 3271 Schülerinnen, geboren zwischen 1981 und 1984, aus drei Provinzen Südpolens erhoben. Das Menarchealter wurde retrospektiv erfragt und basiert auf Angaben zur Menarche von den Studienteilnehmerinnen. Es wurden ANCOVA und multiple Regressionsanalysen verwendet, um Unterschiede zwischen den Gruppen auf statistische Signifikanz zu testen.

Ergebnisse: Mädchen aus Familien der oberen sozio-ökonomischen Schicht menstruieren früher als Mädchen aus Familien niederer sozio-ökonomischer Schichten. Je nach geographischer Region und Populationsgröße gibt es jedoch noch weitere Faktoren, die das Menarchealter beeinflussten. Faktoren, die in der Provinz Krakau signifikanten Einfluss auf das Menarchealter zeigen, sind Urbanisationsgrad, Schulbildung des Vaters und Anzahl der Kinder in der Familie; in der Provinz Oppeln beinhalten diese Faktoren den Urbanisationsgrad und die Anzahl der Kinder in der Familie, während in der Provinz Novy Sacz nur die Anzahl der Kinder in der Familie Signifikanzniveau erreichen.

Zusammenfassung: Sozio-ökonomische Unterschiede sind in einer Großstadt (Krakau) größer und nehmen Einfluss auf die Variation des Menarchealters. In den weniger umfangreichen Populationen (Oppeln, Novy Sacz) aus kleineren Städten und Dörfern ist dagegen der Unterschied im Menarchealter weniger offensichtlich. Darüber hinaus zeigt die Variation zwischen Regionen, dass das Menarchealter in städtischen Gegenden niedriger ist als in ländlichen.

Resumen. Antecedentes: La edad de menarquia es la medida más importante de la maduración sexual en chicas y un sensible indicador de las condiciones ambientales durante la infancia.

Objetivo: El estudio analizó la asociación entre la edad de menarquia y características socioeconómicas (urbanización, tamaño poblacional, educación de los padres y número de hijos en la familia).

Sujetos y métodos: Los datos del cuestionario se recogieron en 3271 niñas escolares nacidas entre 1981 y 1984, que residían en tres provincias del sur de Polonia. La edad de menarquia se estimó por el método retrospectivo y se basó en la fecha de menarquia proporcionada por las participantes en el estudio. Se aplicaron los análisis ANCOVA y de regresión múltiple para comprobar la significación estadística de las diferencias entre grupos.

Resultados: Las chicas de familias con un nivel socioeconómico elevado experimentan la menarquia a una edad más temprana que las de familias con un nivel socioeconómico bajo. Sin embargo, dependiendo de la región geográfica y del tamaño poblacional, existen otros factores que influyen sobre la edad de menarquia. En la provincia de Cracovia, los factores que producen diferencias significativas en la edad de menarquia son la urbanización, la educación del padre y el número de hijos en la familia; en la provincia de Opole, estos factores incluyen la urbanización y el número de hijos de la familia, mientras que en la provincia de Nowy Sacz, es significativo el número de hijos por familia.

Conclusiones: Las diferencias socioeconómicas son mayores en una gran urbe (Cracovia) y afectan a la variación en la edad de menarquia. Sin embargo, dentro de poblaciones más pequeñas (Opole, Nowy Sacz), viviendo en pueblos y aldeas, la diferencia en la edad de menarquia es menos evidente. Además, la variación entre áreas revela una menor edad de menarquia en el medio urbano comparado con las áreas no urbanas.     

Social background and age at menarche in Portuguese university students: A note on the secular changes in Portugal

Menarcheal age of a sample of Portuguese university students (n = 3,366), born between 1972 and 1983, age 18–23 years, was analyzed. The influence of parents' educational level and occupation, family size, birth order, and degree of urbanization of girl's locality of residence during childhood and adolescence were analyzed as well as secular trend in the Portuguese population. Mean age at menarche for girls born in 1983 was 12.32 years. Parents' educational level and occupation did not show any significant influence on mean age at menarche. Place of residence during childhood years and adolescence showed a significant effect on mean age at menarche, with girls from rural places with a later age at menarche than those who spent their childhood or adolescence in urban areas (P ≤ 0.01 and P ≤ 0.05 for childhood and adolescence, respectively). Family size and birth order showed the highest effect. Girls born in small families, with one child, matured earlier (12.32 years) than those born in large families with four or more children (12.67 years), (P ≤ 0.01). Also, girls that were first‐born had an earlier menarche (12.41 years) than those who were third or later (12.58 years, P ≤ 0.01). Regression analysis selected family size and place of residence in childhood as the most important determinants of mean age at menarche in our university students. In this sample, from 1972 to 1983, mean age at menarche remained stable. When we considered published data from all the Portuguese population we found a decrease in mean age at menarche from 15 years for girls born in 1880 to 12.44 for those born in the 1980s. This decrease was the result of great improvements in the social and economic living conditions that occurred in Portugal especially after the 1970s concerning nutrition and health care, among many other environmental factors. Am. J. Hum. Biol. 15:415–427, 2003. ©2003 Wiley‐Liss, Inc.     

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.     

Short Report: 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.     

Age at menarche in Iran

BACKGROUND: Age at menarche and its potential associated factors are reported for 1862 Shiraz (Southern Iran) secondary school girls taking part in a cross-sectional survey selected from the four educational districts of the city. METHODS: Probit analysis was used to estimate age at menarche, principal component analysis (PCA) was applied to analyse socio-economic status (SES). Body mass index (BMI) was used as an indicator of nutrition. RESULTS: Mean +/- SD age at menarche was 12.91 +/- 1.23 years (95% CI: 12.84-12.97). Of all subjects, 33.7% first menstruated in summer. The highest mean age at menarche was 13.01 years in winter. Stress, anxiety and discomfort was seen among 70.3% of subjects at menarche indicating total or partial ignorance of the menstruation phenomenon. Age at menarche decreased as SES improved. Menarcheal age was delayed for underweight subjects. CONCLUSIONS: It is concluded that BMI and SES had the most significant effects on variation of menarcheal age in a unified statistical model. However, their interaction was found to be not statistically significant.     

Age at menarche in Iran

Background : Age at menarche and its potential associated factors are reported for 1862 Shiraz (Southern Iran) secondary school girls taking part in a cross-sectional survey selected from the four educational districts of the city. Methods : Probit analysis was used to estimate age at menarche, principal component analysis (PCA) was applied to analyse socio-economic status (SES). Body mass index (BMI) was used as an indicator of nutrition. Results : Mean &#45 SD age at menarche was 12.91 &#45 1.23 years (95% CI: 12.84-12.97). Of all subjects, 33.7% first menstruated in summer. The highest mean age at menarche was 13.01 years in winter. Stress, anxiety and discomfort was seen among 70.3% of subjects at menarche indicating total or partial ignorance of the menstruation phenomenon. Age at menarche decreased as SES improved. Menarcheal age was delayed for underweight subjects. Conclusions : It is concluded that BMI and SES had the most significant effects on variation of menarcheal age in a unified statistical model. However, their interaction was found to be not statistically significant.     

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.     

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.     

Age at menarche as an indicator of the socioeconomic situation of rural girls in Poland in 1967, 1977, and 1987

Village girls, 9.5–18.5 years of age, inhabiting various regions of Poland, were surveyed in 1967 (n = 7,886), 1977 (n = 7,771), and 1987 (n = 11,479). Based on the source of income of the families, three groups were identified: farmers, farmer-workers, and nonfarmers. The girls were also divided on the basis of the number of children in the family and education of their fathers. In all three surveys, the earliest age at menarche was observed in girls from the nonfarmer group and the latest in girls from the farmer group. In 1987 the ages at menarche were 13.27 ± 0.03 years and 13.58 ± 0.04 years, respectively. The rapid acceleration of menarcheal age (0.64 year) between 1967 and 1977 was halted, and perhaps, reversed from 1977 to 1987 (?0.06 year), reflecting the severe social and economic crisis in Poland. The later menarcheal ages observed in the last decade occur mainly among girls from families with four and five children. Girls from better educated rural families were more affected by the crisis than girls from families in which fathers have only an elementary or vocational training education. © 1995 Wiley-Liss, Inc.     

Socio-demographic predictors of age at menarche in a group of Colombian university women

BACKGROUND: Age at menarche is an important developmental milestone known to be modified by social and environmental factors. The determinants and potential change over time of age at menarche in Colombia are not well documented. AIMS: To obtain a current estimate of age at menarche in Colombia and to examine the associations between socio-demographic characteristics and age at menarche. SUBJECTS AND METHODS: Between 1998 and 2001, we obtained recalled age at menarche, socio-demographic characteristics, and physical activity information in a group of 3206 students at the National University of Colombia who completed a self-administered questionnaire. We examined the cross-sectional associations between mean age at menarche and migratory pattern, parental education, socio-economic status indicators, practice of physical activity, and year of birth using linear regression. RESULTS: Mean age at menarche (+/- SD) was 12.68 +/- 1.31. In a multivariate adjusted regression model, age at menarche was positively associated with family size and the practice of at least 2 daily hours of physical activity, and was inversely related to urbanization level, socio-economic status, and year of birth. CONCLUSIONS: Socio-economic status is a strong predictor of menarche in this population. There appears to be a trend towards earlier menarche by year of birth.     

Socio-demographic predictors of age at menarche in a group of Colombian university women

Background: Age at menarche is an important developmental milestone known to be modified by social and environmental factors. The determinants and potential change over time of age at menarche in Colombia are not well documented.

Aims: To obtain a current estimate of age at menarche in Colombia and to examine the associations between socio-demographic characteristics and age at menarche.

Subjects and methods: Between 1998 and 2001, we obtained recalled age at menarche, socio-demographic characteristics, and physical activity information in a group of 3206 students at the National University of Colombia who completed a self-administered questionnaire. We examined the cross-sectional associations between mean age at menarche and migratory pattern, parental education, socio-economic status indicators, practice of physical activity, and year of birth using linear regression.

Results: Mean age at menarche (±?SD) was 12.68 ± 1.31. In a multivariate adjusted regression model, age at menarche was positively associated with family size and the practice of at least 2 daily hours of physical activity, and was inversely related to urbanization level, socio-economic status, and year of birth.

Conclusions: Socio-economic status is a strong predictor of menarche in this population. There appears to be a trend towards earlier menarche by year of birth.     

Changes in menarcheal age in girls exposed to war conditions

The purpose of this study was to assess changes in mean menarcheal age of girls in the city of Šibenik in the period from mid-1980s to the mid-1990s. Šibenik is a Dalmatian town which was exposed to hard war conditions in 1991–1995. Menarcheal status of Šibenik girls was surveyed three times, in 1981, 1985, and 1996, and included 720, 1,207, and 1,680 girls, respectively, ages 9.5–16.5 years. Mean menarcheal age was estimated by the status quo method and application of probit analysis. Results show a slight decrease in menarcheal age from 1981 to 1985 (from 12.97 ± 0.06 years to 12.87 ± 0.05), and then a significant increase from 12.87 ± 0.05 years in 1985 to 13.13 ± 0.10 years in 1996. The increase in mean menarcheal age occurred in all socioeconomic groups based on parental occupation and number of siblings. In the group of girls whose homes were damaged during war, menarche occurred at an average of 13.53 ± 0.14 years, while those who lost a family member experienced menarche at an older mean age, 13.76 ± 0.27 years. However, when the girls who experienced personal tragedies were excluded the onset of menarche was still later than in girls surveyed in the earlier periods. The results suggest that the general reversal in the secular trend of menarcheal age in Šibenik girls can be attributed to persistent psychological pressures and uncertainties associated with conditions of war. Am. J. Hum. Biol. 12:503–508, 2000. © 2000 Wiley-Liss, Inc.     

Height,weight and menarche in Swedish urban school children in relation to socio-economic and regional factors

During the period 1964–1973, a defined sample of 740 Swedish urban school children (360 girls and 380 boys) from 40 different urban areas all over the country were followed longitudinally. Height and weight were measured twice a year and age at menarche was recorded. Mean ages at peak height velocity (PHV) and peak weight velocity (PWV) were 11·91 years (SD 0·95) and 12·50 years (SD 1·08) for girls with average values of 8·30 cm/year (SD 1·32) and 7·37 kg/year (SD 1·94). Mean age at menarche was 13·05 years (SD 1·03). PHV and PWV in boys occurred on average at 14·09 years (SD 1·11) and 14·30 years (SD 1·11) with magnitudes of 9·84 cm/year (SD 1·40) and 9·07 kg/year (SD 2·04). No significant differences between socio-economic strata defined by father's occupation and family income were found either for height and weight or for ages at PHV, PWV and menarche. Girls but not boys in the lowest social group (III) had more weight for height during puberty than had girls in social groups I and II. Between the three main geographical regions of Sweden some differences were found. Boys in the South were at the ages of 17 and 18 on average heavier than boys from the rest of the country. Boys and girls in the South had PHV, PWV and menarche half a year later than children in Middle Sweden. In an analysis of variance for age at PHV significant interaction terms were found for regions times urbanization. In the South and North age at PHV was earlier the higher the urbanization level, but in Middle Sweden the reverse occurred.     

Evidence for a downward secular trend in age of menarche in a rural Gambian population

Abstract

Menarcheal age is a key indicator of female maturity and development. Studies in many countries have reported a downward secular trend in age of menarche over the past century. This study presents data gained using the ‘status quo’ method and interval regression to estimate median menarcheal age of girls in a rural Gambian community. Cross-sectional studies carried out in 1989, 2000 and 2008 revealed a median menarcheal age of 16.06 (95% CI 15.67–16.45), 15.03 (95% CI 14.76–15.30) and 14.90 (95% CI 14.52–15.28), respectively. The average rate of decline of median age of menarche was amongst the most rapid yet reported, at 0.65 years of age per decade (p < 0.00001). There was no evidence for a change in the rate of decline over the two decades studied. These results probably reflect ongoing socio-economic development within the region.     

Age at menarche: secular trends and association with adult anthropometric measures

Summary. Background: Age at menarche has been used as a marker of environmental conditions during childhood. Previous work has shown trends of decreasing age at menarche throughout the 19th century, but reported trends in the 20th century have been less consistent. The nature of the relationship between age at menarche and adult life anthropometric measures may be important in understanding the importance of this measure on disease in later life. Aim: To establish whether mean age at menarche changed during the first half of the 20th century, and to determine the nature of associations between age at menarche and anthropometric measures in young adulthood. Subjects and methods: 3433 female students, who were born between 1919 and 1952 and who attended health checks at the student health service of the University of Glasgow between 1948 and 1968. Results: Mean age at menarche decreased from 13.2 years in the earliest born to 12.5 years in the latest born students. These results were not explained by changes in socio-demographic factors. Menarcheal age was positively associated with height and negatively associated with weight and BMI, results independent of socio-demographic and behavioural factors. Conclusions: The falling age at menarche described here may be related to nutritional influences in the first half of the 20th century. The influence of menarche on BMI in early adulthood may have important health consequences.     

Age at menarche: secular trends and association with adult anthropometric measures

BACKGROUND: Age at menarche has been used as a marker of environmental conditions during childhood. Previous work has shown trends of decreasing age at menarche throughout the 19th century, but reported trends in the 20th century have been less consistent. The nature of the relationship between age at menarche and adult life anthropometric measures may be important in understanding the importance of this measure on disease in later life. AIM: To establish whether mean age at menarche changed during the first half of the 20th century, and to determine the nature of associations between age at menarche and anthropometric measures in young adulthood. SUBJECTS AND METHODS: 3433 female students, who were born between 1919 and 1952 and who attended health checks at the student health service of the University of Glasgow between 1948 and 1968. RESULTS: Mean age at menarche decreased from 13.2 years in the earliest born to 12.5 years in the latest born students. These results were not explained by changes in socio-demographic factors. Menarcheal age was positively associated with height and negatively associated with weight and BMI, results independent of socio-demographic and behavioural factors. CONCLUSIONS: The falling age at menarche described here may be related to nutritional influences in the first half of the 20th century. The influence of menarche on BMI in early adulthood may have important health consequences.     

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.     

Menarcheal age in Cumbria

A survey of age at menarche in north-west England, how it is affected by family environment and how it affects physique, was carried out on a large sample of schoolgirls in Cumbria. Age at menarche shows no independent effect of social class, but is strongly influenced by family size and also partly by position in family. Similar results emerge from analyses of the status quo and recall data. Menarcheal status differences remain associated with pronounced differences in height and weight when all other variables are held constant, and there is a slight suggestion that the effect diminishes the later the age at which menarche occurs.     

Age at menarche and its influencing factors in North Korean female refugees

BACKGROUND: Age at menarche is known to be regulated by genetic and environmental factors. To date, no menarcheal data are available on North Korean women. In this cross-sectional survey, we investigated age at menarche and its possible influencing factors in North Korean refugees. METHODS: Four hundred and eleven North Korean refugees were surveyed at a North Korean female refugee camp using a structured questionnaire within 3 months of immigration. Menarcheal age was requested and the data obtained were analysed with respect to age at interview, region of residence in North Korea, education, food preference and sleep duration. RESULTS: Mean age at menarche was 16.0+/-2.1 years (mean+/-SD). Univariate analysis demonstrated a significant difference in the menarcheal age among the different food preference groups (P=0.0236). Sleep duration was found to be significantly and negatively correlated with age at menarche (R=-0.23, P<0.0001). However, generalized linear model (GLM) analysis revealed that region of residence at menarche (P=0.0209) and sleep duration (P=0.0007) were significant determinants. Food preference played a role as an effect modifier in the relationship between the region of residence at menarche and age at menarche. CONCLUSION: Age at menarche seemed to be delayed in North Korean refugees. GLM analysis showed that sleep duration and region of residence at menarche were significant influencing factors of age at menarche in this study population.     

The growth of London schoolchildren 1904-1966: an analysis of secular trend and intra-county variation

Height and weight were measured on 299,303 children involved in eleven London County Council Surveys dating from 1904 to 1966. This paper describes the historical background to these surveys, the secular trend towards increasing heights and weights and a decreasing age at menarche, and the variation of height and weight between parts of the county. All the surveys were cross-sectional, but that of 1966 included yearly velocity data on 13,806 children. Means for height and weight by age and sex were adjusted to the exact half year to allow comparison of all surveys. Menarcheal age was determined by probit analysis on status quo data in 1954, 1959 and 1966. Intra-county comparisons were based on the Divisional Index of the nine Area Health Divisions of the County. The results indicate an end to the positive secular trend for height and weight at about the same time as the previously reported end to a decreasing age of menarch in London girls. Intra-county comparisons indicated different rates of secular trend within different areas favouring those children who were the smallest and lighest in 1949. The end of the secular trend is thought to be due to genetic factors and intra-county changes to improve environmental conditions.