Demerath Ellen W, Towne Bradford, Chumlea W Cameron, Sun Shumei S, Czerwinski Stefan A, Remsberg Karen E, Siervogel Roger M
Lifespan Health Research Center, Department of Community Health, Wright State University School of Medicine, Dayton, Ohio 45435, USA.
Am J Hum Biol. 2004 Jul-Aug;16(4):453-7. doi: 10.1002/ajhb.20039.
A number of recent reports suggest that the average age at menarche of US girls has declined over the past 20 years. Because the putative declines in the age at menarche are concurrent with increases in childhood body mass index (BMI), it has been suggested that these two trends may be causally linked. We examined differences in mean age of menarche in Fels Longitudinal Study girls who were born in six 10-year birth cohorts (1930s, 1940s, 1950s, 1960s, 1970s, and 1980s) and simultaneous cohort changes in mean BMI measured cross-sectionally at selected ages from 3-35 years (n = 371). Girls born in the 1980s had a mean age at menarche of 12.34 years, which was approximately 3-6 months earlier than that of girls born previously (P < 0.001). While the mean BMI values at ages 25 and 35 generally increased from the 1930s to the 1970s, the mean BMI during childhood and adolescence remained constant across the six birth cohorts. In summary, we found no evidence that the recent decline in the age at menarche in the Fels Longitudinal Study girls was reflected in concurrent increases in BMI at any point in childhood or adolescence. Conversely, girls born in the 1960s and 1970s have subsequently become heavier in young and mid-adulthood than were girls from earlier birth cohorts, without any concurrent change in the mean age at menarche over that time period. These two findings suggest that population-level shifts in BMI and the timing of menarche are largely independent, although sometimes coincident, processes.
最近的一些报告表明，在过去20年里，美国女孩月经初潮的平均年龄有所下降。由于月经初潮年龄的假定下降与儿童期体重指数（BMI）的增加同时出现，有人认为这两种趋势可能存在因果联系。我们研究了费尔斯纵向研究中出生于六个10年出生队列（20世纪30年代、40年代、50年代、60年代、70年代和80年代）的女孩月经初潮平均年龄的差异，以及在3至35岁选定年龄进行横断面测量的BMI平均水平的同期队列变化（n = 371）。20世纪80年代出生的女孩月经初潮平均年龄为12.34岁，比之前出生的女孩早约3至6个月（P < 0.001）。虽然25岁和35岁时的平均BMI值从20世纪30年代到70年代总体上有所增加，但在六个出生队列中，儿童期和青春期的平均BMI保持不变。总之，我们没有发现证据表明费尔斯纵向研究中女孩最近月经初潮年龄的下降反映在儿童期或青春期任何时间点BMI的同期增加上。相反，20世纪60年代和70年代出生的女孩在青年期和中年期比早期出生队列的女孩更重，而在这一时期月经初潮平均年龄没有任何同期变化。这两个发现表明，BMI的人群水平变化和月经初潮时间在很大程度上是独立的过程，尽管有时会同时出现。
