Asgharnia Maryam, Faraji Roya, Sharami Hajar, Yadak Merhnoosh, Oudi Mona
Guilan University of Medical Sciences, Islamic Republic of Iran.
Oman Med J. 2009 Apr;24(2):95-8. doi: 10.5001/omj.2009.22.
The event of menarche is an exceptional phenomenon, which occurs once in a lifetime. It is the precursor of future fertility. The onset of menarche is mainly dependent on genetic factors, however geographical and nutritional factors among other factors have been attributed to the events of menarche. The aim of this study is to determine the age of onset of menarche and the factors which induce it in northern Iran.
This is a cross sectional study which will assess the onset of menarche in girls between the age of 11-16 years. The subjects were either in middle or high school and had experienced menarche within 6 months prior to the study. This study revolves around 600 girls who were selected using stratified randomized sampling techniques. The data was collected in the form of a questionnaire which focused on age, weight (was measured to the nearest 0.1 kg using a balance beam scale), height (was measured to nearest 0.1cm with a manual height board), and Body Mass Index (BMI: kg/m2) was used as an index of relative weight. Principal Component Analysis (PCA) was applied to analyze Socio-economic Status (SES). The defined standard age of the first menstrual event was applied as the standard. The data collected was analyzed using the Statistical Package for the Social Sciences (SPSS.10) statistical analysis software and the Chi-square and Analysis of Variance (ANOVA) tests were applied. In an effort to establish the factors associated with the age of menarche, multivariate analysis was performed based on linear logistic regression which was performed using a model where all the variables changing the risk estimated by more than 10%. Statistical significance was determined at P<0.05.
The mean age at menarche was observed to be 12.99±1.33yrs (ranging from 10.16 to 15.91 yrs). The study showed that menarche occurred during the summer for 270 (45%) patients making it the most common season for menarche while winter was the least common season. The mean age of menarche was delayed in patients from low SES groups and it occurred earlier in patients from high SES. In girls with low BMI, menarche occurred earlier in comparison to girls with high BMI. There was a significant correlation between session and age of menarche (p<0.05). There was no significant relationship statistically between BMI and age of menarche (p>0.05). Linear regressions showed no significant effect of BMI on the age of menarche but there was a significant correlation between season and SES on the age of menarche.
The age of menarche and the most common seasons for menarche were similar to previous studies. Results from this study showed that the age of menarche decreased with higher SES, and also the age of menarche in girls with high and low BMI occurred earlier. However, previous studies showed that it ocurred earlier in high BMI and later in low BMI. It appears that genetic and environmental factors have influenced these differences.
初潮是一种特殊现象，一生仅发生一次。它是未来生育能力的先兆。初潮的开始主要取决于遗传因素，然而地理和营养等其他因素也与初潮有关。本研究的目的是确定伊朗北部女孩初潮的起始年龄及其诱发因素。
这是一项横断面研究，将评估11至16岁女孩的初潮情况。研究对象为初中或高中学生，且在研究前6个月内经历过初潮。本研究围绕600名使用分层随机抽样技术选取的女孩展开。数据通过问卷形式收集，问卷重点关注年龄、体重（使用平衡梁秤精确测量至最接近的0.1千克）、身高（使用手动身高板精确测量至最接近的0.1厘米），并将体重指数（BMI：千克/平方米）用作相对体重指标。应用主成分分析（PCA）来分析社会经济地位（SES）。将首次月经事件的既定标准年龄作为标准。所收集的数据使用社会科学统计软件包（SPSS.10）进行分析，并应用卡方检验和方差分析（ANOVA）。为确定与初潮年龄相关的因素，基于线性逻辑回归进行多变量分析，该分析使用的模型中所有变量使风险估计变化超过10%。当P<0.05时确定具有统计学意义。
观察到初潮的平均年龄为12.99±1.33岁（范围为10.16至15.91岁）。研究表明，270名（45%）患者的初潮发生在夏季，使其成为初潮最常见的季节，而冬季是最不常见的季节。低社会经济地位组患者的初潮平均年龄延迟，而高社会经济地位组患者的初潮发生得更早。与高BMI女孩相比，低BMI女孩的初潮发生得更早。初潮时间与初潮年龄之间存在显著相关性（p<0.05）。BMI与初潮年龄之间在统计学上无显著关系（p>0.05）。线性回归显示BMI对初潮年龄无显著影响，但季节和社会经济地位与初潮年龄之间存在显著相关性。
初潮年龄和初潮最常见的季节与先前研究相似。本研究结果表明，初潮年龄随社会经济地位升高而降低，高BMI和低BMI女孩的初潮年龄也更早出现。然而，先前研究表明高BMI女孩初潮更早，低BMI女孩初潮更晚。似乎遗传和环境因素影响了这些差异。
