Definition: The secular trend refers to the average age of puberty decreasing over time. Since the 1900s in the United States, puberty seems to have occurred about 4 months earlier with each passing decade.
Scientists debate whether the secular trend is continuing to occur. Some say that the secular trend may have leveled off in the 1970s. There is evidence, however, that girls are currently experiencing earlier breast development than in previous decades. Whether age of first period (menarche) is continuing to decrease remains debated.
The secular trend has important biological and psychological consequences.
Related terms: menarche, precocious puberty
Sources:
Biro, Frank M., et al. (2010). Pubertal assessment method and baseline characteristics in a mixed longitudinal study of girls. Pediatrics. Retrieved August 13, 2010:
Walvoord, Emily C. The timing of puberty: Is it changing? Does it matter? Journal of Adolescent Health. 2010. 1-7.