Sex differences in the secular changes in pubertal maturation.
It is a common experience among pediatricians in the industrialized countries that many girls-but many fewer boys-present with secondary sex characteristics at a younger age than normal. This study examines whether there are sex differences in the secular changes toward earlier pubertal maturation. The author collected the growth data from various studies performed in Greece in the 20th century (from 1928 to 1995) and estimated the age at peak annual height increment in each study by calculating mean increase in height in each successive year. In all studies, boys presented peak mean annual height increment at 13 to 14 years of age. Girls did not present a discernible peak height increment until the late 1960s; however, thereafter they presented a peak height increment at 11 to 12 years of age. The data suggest sex differences in the secular changes in pubertal maturation, girls being affected more intensely than boys.