NCPA - National Center for Policy Analysis

No Change Found In Age Of Menarche

May 4, 2001

A new study in the British Medical Journal confirms that there has been little change in the average age of menarche (age at first period) in British teenagers during the past 20-30 years. This finding contradicts claims previously made in America that man-made chemicals, so-called endocrine disruptors, in the environment are disrupting human hormonal development.

Over 1,000 girls aged 12-16 in schools across 10 British towns completed a questionnaire about their first period.

  • The survey found the average menarcheal age was 12 years 11 months, with almost 12 percent reporting they had had their first period before leaving primary school.
  • Average ages were similar in different regions and did not differ by social class or ethnic group.

The results clearly show that any decrease in average menarcheal age during the past 20-30 years has been small (almost certainly less than six months), particularly when compared with the reduction of a year or more that occurred in many European countries (including Britain) between the late 19th and mid 20th centuries, conclude the authors.

Source: P. H. Whincup et al., "Age of menarche in contemporary British teenagers: survey of girls born between 1982 and 1986," British Medical Journal, May 5, 2001.

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