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Secular trends in age at menarche in Norwegians born from 1840 to 2008
Ingvild Særvold Bruserud1,2, Edda Greaker3, Martin Flatø4,5
1Children and Youth Clinic, Haukeland University Hospital, Bergen, Norway.
Background:
It is uncertain if age of menarche continues to decline. There has been no systematic meta-analysis of ages at menarche in Norway the past three decades.
Aim:
To conduct a systematic review and meta-analysis to assess secular trends in menarcheal age in Norway.
Subjects And Methods:
A literature search was performed in PubMed, Web of Science, and Embase to identify studies including ages at menarche from healthy females. Re-analysis of data from 16 surveys were included together with 17 published studies in a meta-analysis using weighted regression analyses with fitted restricted cubic splines. Each study or dataset was given a random intercept to account for within-survey correlation.
Results:
In total, 783,757 observations were included in the meta-analysis. Three distinct periods were identified. For women born 1840-1910, a large and stable decline with -0.14 to -0.20 years per decade (y/d) was observed, whilst in women born 1910-1950 this decline accelerated up to -0.30 y/d. The third period of women born 1950-2008 saw a small and stable decline with -0.06 to -0.08 y/d.
Conclusion:
Age at menarche declined throughout the study period from 1840-2008, but more rapidly in girls born between 1910-1950. Data suggest an ongoing, modest decline.
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