日本 1930 年至 1985 年出生的女性月经初潮年龄和规律月经周期建立时间的长期变化趋势。
Secular trends in age at menarche and time to establish regular menstrual cycling in Japanese women born between 1930 and 1985.
机构信息
Faculty of Health Care, Takasaki University of Health and Welfare, Takasaki City, Gunma Prefecture, Japan.
出版信息
BMC Womens Health. 2012 Jul 16;12:19. doi: 10.1186/1472-6874-12-19.
BACKGROUND
Early life-stage exposure to estrogen increases the risk of breast cancer. The objective of this study was to investigate the age at menarche and time to onset of regular menstrual cycles for Japanese women born between 1930 and 1985.
METHODS
A cross-sectional study was designed using data from the baseline survey of the Japan Nurses' Health Study. The data from 48,104 female nurses were analyzed. To view trends in age at menarche, the distribution of age at menarche was calculated for each birth year cohort. The distribution of time to onset of regular menstrual cycles was calculated for each birth year cohort. To estimate whether high-risk group of the estrogenic dependent disorders increase with succeeding generations, we defined the women who experienced menarche at ten years old or younger and started a regular cycle within one year as early age onset of ovulatory cycles.
RESULTS
Average ages at menarche were as follows: 13.8 years for those born in the 1930s (n = 113), 13.3 years for the 1940s (n = 4,751), 12.8 years for the 1950s (n = 15,844), 12.3 years for the 1960s (n = 20,547), 12.2 years for the 1970s (n = 6,568), and 12.2 years for the 1980s (n = 281). The proportion of women who experienced the onset of regular menstrual cycles 1 year after menarche was 29.3% for those born in the 1930s, but decreased to 11.9% for the 1980s. On the other hand, the proportion of women who did not have regular menstrual cycles was 10.4% for those born in the 1930s, but rose to 19.8% in 1980s. The proportion of women who experienced menarche at 10 years old and started regular menstrual cycles within one year increased over time: the percentage was 0.0%, 0.4%, 0.6%, 1.1%, 1.3%, and 2.1% for the women born in 1930s, 1940s, 1950s, 1960s, 1970s, and 1980s, respectively.
CONCLUSIONS
The age at menarche of Japanese women born between 1930 and 1985 decreased, but the onset of regular menstrual cycling is delayed; so that the distribution of the start time of ovulatory cycles may have spread for younger generations. Those suggest that the high-risk group of estrogenic dependent diseases among Japanese women may increase in the near future.
背景
早期生命阶段暴露于雌激素会增加乳腺癌的风险。本研究的目的是调查 1930 年至 1985 年出生的日本女性的初潮年龄和规律月经周期开始的时间。
方法
本研究采用日本护士健康研究基线调查的数据进行了一项横断面研究。对 48104 名女性护士的数据进行了分析。为了观察初潮年龄的趋势，我们为每个出生年份的队列计算了初潮年龄的分布。为每个出生年份的队列计算了规律月经周期开始的时间分布。为了估计雌激素依赖疾病的高危人群是否随代际增加，我们将初潮年龄为 10 岁或更小且一年内开始规律周期的女性定义为排卵周期的早期发病。
结果
不同年代出生的女性初潮年龄的平均值如下：20 世纪 30 年代出生的女性为 13.8 岁（n = 113），20 世纪 40 年代出生的女性为 13.3 岁（n = 4751），20 世纪 50 年代出生的女性为 12.8 岁（n = 15844），20 世纪 60 年代出生的女性为 12.3 岁（n = 20547），20 世纪 70 年代出生的女性为 12.2 岁（n = 6568），20 世纪 80 年代出生的女性为 12.2 岁（n = 281）。初潮后 1 年开始规律月经周期的女性比例为 29.3%，但在 20 世纪 80 年代下降到 11.9%。另一方面，初潮后无规律月经周期的女性比例为 10.4%，但在 20 世纪 80 年代上升到 19.8%。初潮年龄为 10 岁且初潮后一年内开始规律月经周期的女性比例随时间增加：20 世纪 30 年代、40 年代、50 年代、60 年代、70 年代和 80 年代出生的女性分别为 0.0%、0.4%、0.6%、1.1%、1.3%和 2.1%。
结论
1930 年至 1985 年出生的日本女性的初潮年龄下降，但规律月经周期的开始时间延迟；因此，排卵周期开始时间的分布可能已经向年轻一代扩散。这些表明，日本女性中雌激素依赖疾病的高危人群可能在不久的将来增加。
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