Age at menarche of European, Afro-Caribbean and Indo-Pakistani schoolgirls living in London.

Age at menarche is reported for 1,365 European, 530 Afro-Caribbean and 282 Indo-Pakistani schoolgirls taking part in a cross-sectional anthropometric survey in the London Area Health Authorities of Kensington, Chelsea and Westminster, and Brent and Harrow, in 1980-81. Mean ages at menarche are 13.59 +/- 0.37 years (European), 13.18 +/- 0.11 years (Afro-Caribbean) and 13.06 +/- 0.20 years (Indo-Pakistani). The European value is significantly higher than those for Afro-Caribbean and Indo-Pakistani girls, and for Europeans living in the same areas of London in 1966. Social class has an effect on age at menarche in Afro-Caribbean and European girls, but not Indo-Pakistani girls, whilst family size has an effect on age at menarche in Europeans and Indo-Pakistanis.