title: Secular trends in age at menarche in women in the UK born 1908-93: results from the Breakthrough Generations Study.
abstract: Menarcheal age decreased over time in Western countries until cohorts born in the mid-20th century. It then stabilised, but limited data are available for recent cohorts. Menarche data were collected retrospectively by questionnaire in 2003-10 from 94,170 women who were participating in the Breakthrough Generations Study, aged 16-98 years, born 1908-93 and resident in the UK. Average menarcheal age declined from women born in 1908-19 (mean=13.5 years) to those born in 1945-49 (mean=12.6 years). It was then stable for several birth cohorts, but resumed its downward trend in recent cohorts (mean=12.3 years in 1990-93 cohort). Trends differed between socio-economic groups, but the recent decline was present in each group. In conclusion, menarcheal age appears to have decreased again in recent cohorts after a period of stabilisation.
authors.affiliation: Section of Epidemiology, Institute of Cancer Research, Sutton, Surrey, UK. danielle.morris@icr.ac.uk
authors.forename: Danielle H
authors.initials: DH
authors.lastname: Morris
authors.forename: Michael E
authors.initials: ME
authors.lastname: Jones
authors.forename: Minouk J
authors.initials: MJ
authors.lastname: Schoemaker
authors.forename: Alan
authors.initials: A
authors.lastname: Ashworth
authors.forename: Anthony J
authors.initials: AJ
authors.lastname: Swerdlow
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008572:Menarche / Q000502:physiology*; D008875:Middle Aged; D011157:Population Dynamics; D012189:Retrospective Studies; D012959:Socioeconomic Factors; D011795:Surveys and Questionnaires; D006113:United Kingdom; D055815:Young Adult