AGE AT MENARCHE OF MOTHERS AND DAUGHTERS, WITH A NOTE ON ACCURACY OF RECALL

Among 66 white mothers and their 78 daughters, the latter serving as subjects in a completed longitudinal growth study, the daughters' mean age at menarche was 12.88 years, the mothers' 14.38 years (p < 0.001). This 1.5-year advance exceeds the estimate for the secular trend in the general population, 1 year per generation. The daughters' recall, 19 years after the event, was unbiased in direction, if only moderately accurate: mean ages of actual and recalled meagrche were within two months; 77% of recalled dates were within one year, 92% within two years, and 100% with 2.5 years of the actual date. The coefficient of correlation for menarcheal age between mothers and daughters was 0.24 ± 0,11 (p < 0.05), and for stature 0.41 ± 0.11. Age at menarche was independent of adult stature in both groups. Although the daughters were 1.19 inches (3.02 cm) taller as adults than their mothers—exceeding the estimated value, less than 1 inch (2.54 cm) per generation, for the secular trend—, acceleration of menarche was independent of increase in stature (r=0.01 ± 0.13). This suggests that physical growth and sexual maturation may be separate processes. Nutritional differences between mothers and daughters could account for only part of the advance in menarche. Improved health and some as yet unspecified aspects of the material and psycho-social environment presumably account for the rest.