Related Experiment Video
Updated: Feb 1, 2026

The Resident-intruder Paradigm: A Standardized Test for Aggression, Violence and Social Stress
Published on: July 4, 2013
Age at menarche and place of residence (Marrakesh, Morocco)
1Laboratory of Human Ecology, Faculty of Science Semlalia, Cadi Ayyad Marrakesh University, Avenue Prince Moulay Abdellah, BP 2390, Marrakesh, Morocco.
Purpose:
The aim of the study was to determine the age at menarche of Moroccan girls by place of residence (rural vs. urban).
Methods:
The data were derived from a survey conducted between 2014 and 2016 in schools of the Marrakesh region. A total of 433 questionnaires were completed by 433 girls aged 9-18 years, with 245 (56.6%) living in urban areas and 188 (43.4%) in rural areas. The mean and median age at menarche of the girls were estimated by retrospective and status-quo methods, respectively. The sociodemographic variables used were the parents' educational level, the parents' socioeconomic status, and family size.
Results:
Out of the 433 girls surveyed, 265 had attained menarche, and the mean was at 13.10 years. The median age at menarche was 13.46 years. According to the place of residence, the girls living in urban areas on average had their first menstruation earlier than girls from rural areas. The mean and median ages at menarche of urban girls were 12.96 years and 13.16 years, respectively, compared with 13.34 years and 13.94 years for their rural counterparts.
Conclusion:
What can be inferred from this study is that the place of residence is a differential factor of age at menarche. This can be related to differences in the living conditions between the two environments.
Related Concept Videos
Aging
Cellular Clock Theory
The cellular clock theory posits that the human lifespan is closely tied to the finite capacity of cells to divide, a phenomenon governed by telomeres, which are protective caps at the ends of...
Noncompartmental Analysis: Mean Residence Time
After the administration of a drug through intravenous bolus injection, the drug molecules are distributed throughout the body and remain there for varying periods. The MRT represents the average time these drug molecules stay in the...
The Effect of Aging on Tissues
Changes in the Appendicular Skeleton with Age
Initially, the limb buds consist of a core of mesenchyme covered by a layer of ectoderm. The ectoderm at the end of the limb bud thickens to form a narrow crest called the apical ectodermal ridge. This ridge stimulates the underlying...
Pharmacodynamics in Geriatric Patients: Effects of Age
Pharmacokinetics in Geriatric Patients: Effect of Age on Drug Absorption

