ABSTRACT
INTRODUCTION: Menarche or first menstrual period is a landmark in reproductive life span and it is the most prominent change of puberty. The timing of menarche can be under the influence of genes as well as individual environmental factors interacting with genetic factors. OBJECTIVE: Our study objectives were (a) to investigate the heritability of age of menarche in twins, (b) to obtain the association between age of menarche and childhood factors, and reproductive events/behavior, (c) to examine whether or not having a male co-twin affects early/late menarche. METHODOLOGY: A group of female-female identical (n = 108, 54 pairs), non-identical twins (n = 68, 34 pairs) and 17 females from opposite-sex twin sets were identified from twin registries of Malaysia and Iran. Genetic analysis was performed via two methods of Falconers’ formula and maximum likelihood. RESULTS: Heritability was found to be 66% using Falconers’ formula and 15% using univariate twin analysis. Model analysis revealed that shared environmental factors have a major contribution in determining the age of menarche (82%) followed by non-shared environment (18%). DISCUSSION: Result of this study is consistent with that of the literature. Timing of menarche could be under the influence of shared and non-shared environmental effects. Hirsutism was found to have a higher frequency among subjects with late menarche. There was no significant difference in age of menarche between females of opposite-sex twins and females of same-sex twins. CONCLUSION: It is concluded that twin models provide a powerful means of examining the total genetic contribution to age of menarche. Longitudinal studies of twins may clarify the type of environmental effects that determine the age of menarche.
Subject(s)
Age Factors , Environment , Female , Humans , Iran , Malaysia , Menarche/genetics , Puberty , Registries , Reproductive HealthABSTRACT
The age at menarche is an indicator of racial, geographical and nutritional patterns of different societies. This cross-sectional study conducted on 1223 girls aged 14-20 in the Markazi (Central) Province, Iran in 2010. In this research, the age at menarche, as the main variable, was determined for each city and compared between different cities. The statistical analyses included c2 test for determining statistically significant differences, variance analysis for determining the difference between groups, and Pearson correlation coefficient for determining the relationship between variables. The average age of first menstruation was 13.21+/-1.33 years in the Markazi Province, with no significant difference among the cities of the province. This age is inversely related to body mass index (BMI), nutritional status and weight. The pattern of distribution of BMI is similar for all the cities in the province. Although, the average age at menarche in the Markazi (central) Province, a cold area, is higher compared to warmer regions in Iran, it may be more influenced by race than by the climate. Considering the lower age at menarche in Markazi Province compared to previous similar studies, it may be stated that social well-being and nutritional standards have improved in the province.
La edad de la menarquia es un indicador de patrones raciales, geográficos y nutricionales de distintas sociedades. Este estudio transversal fue realizado el 2010 en 1223 niñas entre 14 y 20 años en la Provincia Markazi (Central), Irán. En esta investigación, la edad de la menarquia, como la variable principal, se determinaron para cada ciudad y en comparación entre las diferentes ciudades. Los análisis estadísticos incluyeron la prueba c2 para determinar diferencias estadísticamente significativas, el análisis de varianza para determinar la diferencia entre los grupos, y el coeficiente de correlación de Pearson para determinar la relación entre las variables. El promedio de edad de la primera menstruación fue 13,21+/-1,33 años en la provincia de Markazi, sin diferencias significativas entre las ciudades de la provincia. Esta edad es inversamente proporcional al índice de masa corporal (IMC), el estado nutricional y el peso. El patrón de distribución del IMC es similar para todas las ciudades de la provincia. Aunque la edad media de la menarquia en la Provincia Markazi (central), una zona de clima frío, es mayor en comparación con las regiones más cálidas en Irán, puede estar más influenciadas por la raza que por el clima. Teniendo en cuenta la baja edad de menarquia en la Provincia Markazi en comparación con estudios similares anteriores, se puede afirmar que el bienestar social y los niveles de nutrición han mejorado en la provincia.
Subject(s)
Female , Fertility/physiology , Fertility/genetics , Menarche/ethnology , Menarche/genetics , Anthropometry/methods , Nutritional Status/ethnology , Cross-Sectional Studies/methods , Growth , IranABSTRACT
Sickle cell hemoglobinopathy has emerged as a major public health problem in the tropical countries of the world including India. This paper deals with the age at menarche and first conception of women in relation to sickle cell genotypes. The mean age at menarche was slightly higher in sickle cell affected girls compared to controls. The delay in onset of menarche affects the age at first conception of the sickle cell afflicted individuals.
Subject(s)
Adolescent , Adult , Anemia, Sickle Cell/epidemiology , Child , Cross-Sectional Studies , Developing Countries , Female , Humans , India/epidemiology , Menarche/genetics , Pregnancy , Pregnancy Complications, Hematologic/bloodABSTRACT
The age at menarche in relation to ABO blood group phenotypes and haemoglobin-E genotypes has been studied among 290 girls belonging to Mongoloid ethnic stock in the North Eastern region of India. The study shows that the age at menarche is influenced by the abnormal haemoglobin E genotype as well as ABO blood group phenotype. Thus, the genetic markers play a pivotal role in the growth and development of an individual.