Onset of puberty at eight years of age in girls determines a specific tempo of puberty but does not affect adult height

Aims: To analyse the effect of early puberty (onset between 7.5 and 8.5 y) on pubertal growth and adult height in girls, and the implications of this effect for the age limit for normal onset of puberty. Methods: Longitudinal study in Reus (Spain) of 32 girls with early puberty until they reached adult height. Data from these girls were compared with longitudinal data from girls (116) from the same population with normal onset at 10 (n = 37), 11 (n = 47), 12 (n = 19) and 13 (n = 13)y. We analysed height, target height, adult height, pubertal height increase, duration of pubertal growth, age at menarche and time to menarche. Results: The adult height of girls with early puberty (160.9 ± 5.4 cm) was similar to that of girls with onset at later ages (p = not significant). In these girls, puberty lasted 5.4 ± 0.7 y and the mean growth during puberty was 31.1 ± 3.5 cm. As the age of onset of puberty increases, the duration of puberty and mean growth during puberty progressively decreased (p < 0.001). Girls with early puberty reached menarche at a mean age of 10.9 ± 1.0 y, 3.2 ± 0.9 y after onset of puberty, and this time span was greater than in the other groups. Conclusion: Girls with onset of puberty at 8 y show all the compensatory phenomena related to height at onset, pubertal duration and height increase during puberty. These phenomena cause their adult height to be similar to that of girls who begin puberty at the age of 10 to 13 y.