[Longitudinal study of the pattern of pubertal development in Cantonese schoolgirls].

OBJECTIVE

To investigate the pattern of pubertal development in healthy Cantonese schoolgirls.

METHOD

From 1992 to 2001, 311 normal Cantonese schoolgirls, ages from 6.25 to 8.83 yrs (7.24 +/- 0.38) at baseline, were followed up until they reached their final adult height (age 15.72 +/- 0.84 yrs, n = 238). Annual physical examinations including height and weight measurement were performed. From the 3rd visit, pubertal maturations (breast and pubic hair development) were also assessed annually until they were 14.5 years. Age of menarche was recorded.

RESULT

(1) Median age at the entry of puberty (age at reaching B2) was 9.83 years (9.33-10.33). Median age at initiation of pubic hair development (PH2) was 10.67 (9.92-11.38) years. Menarche occurred at (12.35 +/- 1.30) years. The age at reaching B2, age at reaching PH2 and age of menarche were all later than that observed in the cross-section study performed in 2003, Guangzhou, China. Peak height velocity (PHV) was reached at (10.52 +/- 1.07) years, 1.00 (0.50-1.50) years after B2 was reached. Interval between "age at onset of breast development" and "age at menarche" was 2.92 (2.08-3.67) years. Duration of pubertal growth (defined as the time from age at B2 to age at which adult height was attained) was (4.80 +/- 0.85) years. (2) Average final adult height (FAH) was (158.74 +/- 5.74) cm. As compared with the cross-section studies held in Guangzhou, China, the FAH in our study was higher than that observed in 1985 but was lower than that observed in 2003. (3) Multiple linear regression analyses showed that the age reaching B2 was an independent factor associated with the age of menarche. (4) Durations of breast stages, interval between B2 and menarche and duration of pubertal growth were similar to that reported in the longitudinal studies in the United Kingdom (1969), Senegal (1995-2000), the United States (1986-1996).

CONCLUSION

In healthy Cantonese schoolgirls, the timing of sexual maturation was in a trend of decline in the past 20 years, however it may have no significant impacts on the tempo of pubertal development and FAH.