Study design
A cross sectional study was conducted in two small towns of Dabat and Kola Diba, northwest Ethiopia, between April and May 2007. These districts were selected for the reason that they are University of Gondar Team Training Program field sites. The study sites have also presented another comparative advantage, each representing a highland and a lowland area respectively.
Study area
Dabat, a highland area with an altitude of 2754 meters above sea level, is found at a distance of 70 kms to the North of the city of Gondar. It has an estimated population of 15,870[8]. On the other hand, Kola Diba, a lowland area 2000 meters below sea level has a population of 16,035. It is located at a distance of 35 kms to the South of the city of Gondar [9].
Sampling
There was one high school in each of the study areas. Only grade 9 and 10 students were selected for the survey because the majority of 9th and 10th graders fall in the ideal age groups to study post menarcheal menstruation pattern. Sample size was calculated assuming 95% confidence level, 50% high risk prevalence (for the sake of having larger sample size it was considered taking 50% as appropriate) and acceptable difference of 4%.
Assuming a non response rate of 10% the total sample size stood at 622.
Equal number of students from the schools of Koladiba and Dabat were enrolled. In each classroom a systematic sampling method was used to identify the sample population after the male students made leave the classrooms. All female students (622) cooperated in answering the questionnaire in their classrooms under the supervision of the research team. Only 612 of the female students were included in the final analysis, partly because many of the girls did not report their exact dates of birth or age at menarche. Of the 612 girls, 305 were from Koladiba while 307 were from Dabat High School.
Data collection
A self-administered questionnaire prepared in Amharic, the mother tongue of all the respondents, and pre-tested on school girls of a similar nearby area was used for collecting the most relevant data from the study subjects. The questionnaire included socio demographic information about the respondent's age, marital status, education level, ethnic group and residence. Localities with 2000 or more inhabitants are considered urban.
Questions related to menstruation comprised menarcheal age, menstrual pattern (regularity of cycle, cycle length, duration of flow, amount of flow), premenstrual symptoms, dysmenorrhea and severity of dysmenorrhea and associated symptoms, impact of menstrual disorder on school attendance, the source of information about menarche and whether they required medical help (from a physician, nurse or midwife) for menstrual disorder or not.
The age at menarche was determined by questioning the girl if she had or not had her menstruation and at which age she had menstruated (0.5 years were systematically added to the age obtained). Then the ages of menarche were grouped in three classes of menarche (early, medium and late). Early menarche is considered 12 years or less, medium menarche between 13 and 14 years and delayed menarche more than 14 years[10, 11].
Explanation on the relevance of the study to the female students was given before they filled the questionnaire. Besides, male students were not in the class while females were filling the questionnaires. Questionnaires were distributed and collected on the same day to ensure confidentiality and prevent information contamination.
Data analysis
The data were analyzed using Epi Info 2000(CDC, Atlanta, Georgia) and SPSS v13 (SPSS Inc, Chicago). Data were analyzed using the χ2 test, t- test and logistic regression analysis. For information obtained by status quo procedure the age at menarche was calculated by probit analysis. P < 0.05 was considered to show statistical significance.
However, owing to some missing answers to certain survey questions, the denominator used in percentage computation varies according to the responses obtained for the survey question.
Ethical approval was obtained from the Institutional Review Board of the College of Medicine and Health Sciences of the University of Gondar. Permission to conduct the study was also obtained from the principal's of participating schools. The purpose of the study was explained to the students and verbal consent was obtained from them regarding their agreement to participate in the study. No name was recorded in order to keep the identity of respondents anonymous.