US
"In an epidemiological survey of the reproductive history of a large
group of United States women who had given birth to at least one
child, there was a secular trend in age at menarche between those born
around 1920 and those born around 1940-45. The trend was linear and
the increment 3.2 months (+/- 0.36) per decade. The women were White,
well nourished, middle-class and resided in all parts of the United
States."
Wyshak, G. Secular changes in age at menarche in a sample of US women.
Ann Hum Biol. 1983 Jan-Feb;10(1):75-7.
Japan
"An attempt is made to clarify the special characteristics of the
secular trend of the menarchial age in Japan. ... conducted in
1979-1980 on 284 school girls born between 1961 and 1966. ... The
arithmetic mean of the age at menarche was 12.40 years with a range of
9.63 to 15.44 years. In 1958 research was conducted on the menarche of
309 girls in the same school, and the mean menarchial age was reported
to be 13.27 years with a range of 10.83 to 16.92 years. The rate of
acceleration during these 21 years was 4.4 months/decade. Mean
menarchial ages obtained in 157 studies ever reported in Japan were
plotted against the year of publication. No definite tendency was
apparent until a gradual change toward earlier menstruation began in
about 1920. In the next 20 years the average decreased from 15.0 to
14.2 years of age. The rate of decrease during the 1920-1940 period
was about 4 months/decade. Due to World War 2, a retardation of
menarche began in 1941 and reached a peak of about 15.0 years of age
in 1950-1952, after which the trend changed into one of rapid
acceleration."
Hoshi, H; Kouchi, M. Secular trend at the age at menarche of Japanese
girls with special regard to the secular acceleration of the age at
peak height velocity. Human Biology. 1981 Dec;53(4):593-8.
Netherlands
"Since 1858, an increase of mean stature has been observed in the
Netherlands, reflecting the improving nutritional, hygienic, and
health status of the population. In this study, stature, weight, and
pubertal development of Dutch youth, derived from four consecutive
nationwide cross-sectional growth studies during the past 42 y, are
compared to assess the size and rate of the secular growth change. ...
In girls, median age at menarche has decreased by 6 mo during the
past four decades to 13.15 y.
Fredriks AM, van Buuren S, Burgmeijer RJ, Meulmeester JF, Beuker RJ,
Brugman E, Roede MJ, Verloove-Vanhorick SP, Wit JM. Continuing
positive secular growth change in The Netherlands 1955-1997. Pediatr
Res. 2000 Mar;47(3):316-23.
Belgium
"The age at menarche in a national sample of 4894 Flemish schoolgirls
was surveyed in 1979-1980. The probit estimate of the mean age at
menarche was 13.20 +/- 0.02 years (SD = 1.25 years). ... Status quo
secular data for the 20th century indicate a decline in estimated mean
ages at menarche of Flemish girls from about 14.3 years before World
War II to 13.6 and 13.2 years, respectively, among girls born just
before and during the war. Subsequently, mean ages at menarche of
Flemish girls are fairly stable between 13.0 and 13.2 years. These
secular changes are of the same magnitude as those observed in other
European countries."
Wellens, R, Malina, RM, Beunen G, Lefevre J. Age at menarche in
Flemish girls: current status and secular change in the 20th century.
Ann Hum Biol. 1990 Mar-Apr;17(2):145-52.
more China
"Southern Chinese girls aged 11 years and 9 months to 12 years and 3
months in Hong Kong have a mean menarcheal age of 11.50 years
(standard deviation of 0.47) using the recollection method. Highly
significant differences are found when compared to the 12-year-old
girls in Hong Kong studied in the past decades. Therefore, a secular
trend of earlier menarcheal age is demonstrated.
So, LL, Yen, PK. Secular trend of menarcheal age in southern Chinese girls.
Z Morphol Anthropol. 1992 Jun;79(1):21-4.
also
Huen, KF, Leung, SS, Lau, JT, Cheung, AY, Leung, NK, Chiu, MC. Secular
trend in the sexual maturation of southern Chinese girls. Acta
Paediatr. 1997 Oct;86(10):1121-4.
"In 1993, a cross-sectional study of sexual maturation of normal
Chinese schoolgirls was performed in Hong Kong. The aim of the study
was to obtain an up-to-date reference for normal pubertal development
in Chinese girls. ... Menstrual status was recorded in 6467 girls over
6 y of age. ... The median age of menarche was 12.38 (95% CI
11.98-12.78) years. ... When comparison is made with similar studies
done in 1962 and 1979, a significant downward secular trend in sexual
maturation is observed (p < 0.01). Except for breast development the
downward secular trend in sexual maturation appears to be diminishing
and may be coming to a halt in the Chinese girls in Hong Kong. Their
median ages of sexual maturation are now among one of the earliest
medians recorded in the world population studied."
further evidence that the downward trend may be bottoming out in some countries
UK
"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."
Cameron, N. The growth of London schoolchildren 1904-1966: an analysis
of secular trend and intra-county variation. Ann Hum Biol. 1979
Nov-Dec;6(6):505-25.
Belgium (see also Belgium above)
"Changes such as an increase in stature, in weight and an earlier
physical and sexual maturation have been observed since the 19th
century in Belgium as in most industrialized countries. In this paper,
we consider the secular trend in height, weight and puberty
(especially menarche) over the last 20 years in Brussels. During the
period 1980-1982, 4177 subjects, from the Belgian population of
Brussels, aged 3-26 years, have been measured and compared with
Belgian subjects living in Brussels in 1960. In our sample, we observe
a statistically significant increase in height (and weight), but this
trend is less rapid than the increases noticed before in Belgium.
Status quo data on menarche from 1048 girls from this sample were
analysed by centiles and the probit method. For the first time in
Belgium, it seems that the median age is stabilized at 13.0 years.
However, the number of late menarches is still evolving."
Vercauteren, M, Susanne, C. The secular trend of height and menarche
in Belgium: are there any signs of a future stop? Eur J Pediatr. 1985
Nov;144(4):306-9.
Denmark
"A halt in the decrease of menarcheal age has been reported in some
countries but has not been documented in Denmark. METHODS: The entire
population of schoolgirls, attending grades 5 through 10 (n=979), in a
particular region of Denmark was investigated by the status quo method
in 1996. Similar investigations had been made in the same region and
by the same method in 1966 and 1983. Mean age and standard deviation
were estimated by probit analysis. Mean age was 13.00 years
(s.e.=0.080; s.d. = 1.15) and almost identical with the mean age in
1983 (13.03 years), but significantly different from the mean age in
1966 (13.40 years). CONCLUSION: The results indicate a halt in the
secular trend towards earlier menarche in the region at some time
between 1966 and 1983."
Helm, P, Grolund, L. A halt in the secular trend towards earlier
menarche in Denmark. Acta Obstet Gynecol Scand. 1998
Feb;77(2):198-200.
Poland
"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. ... 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."
Hulanicka, B, Waliszko, A. Deceleration of age at menarche in Poland.
Ann Hum Biol. 1991 Nov-Dec;18(6):507-13. |
