北安县城地处黑龙江省北部,镇内人口约十六万。气候寒冷,一年中有近半年时间要着冬装。这样环境下女学生的月经初潮情况如何?因而进行了这次女学生月经初潮的调查。调查方法一、对象:一九八一年三月四日至四月二十七日先后调查了城内有代表性的三所中学和二所小学,从小学四年级到高中二年级 Bei’an County is located in northern Heilongjiang Province, the town population of about 160,000. Cold weather, nearly a year in a year to winter wear. Under such circumstances, what is the condition of the menstrual cramps for the female students? Therefore, the survey on the menarche of the girl students was carried out. Method of Investigation I. Object: From March 4 to April 27, 1981, three secondary schools and two primary schools representative of the city were successively investigated. From the fourth grade to the second year of high school