Researchers from Sweden recently published their findings in medical journal JAMA Pediatrics, their study spanning about 50 years in sample size. The boys judged in the Swedish study were born from 1947 to 1996, and 4,090 boys comprised the rather large study group.
The most interesting finding? Boys born closer to the end of the 50-year window were entering puberty before boys who were born closer to the middle of the 20th century. The researchers judged the onset of puberty by something they called “peak height velocity” or PHV — also known as a growth spurt.
At the end of the day, boys born in 1947 hit their primary growth spurts a full month and a half later than boys born in 1996. Boys born in the ’40s saw their first major increase in height at an average age of 14.2, while boys born in 1996 were hitting that milestone at an average age of 13.7.
Is BMI to blame? The researchers place at least some importance on the correlation between an increase in average weight among teenage boys over the years and earlier growth spurts, but that may not be the entire story. Other than the fact that boys born in later years may have more access to junk food, fast food and more calorie-dense food choices, hormones may also play a large role in this earlier onset of puberty.
There are a couple of issues with the study, as well. The sample group was limited to Swedish boys of a largely Caucasian background. Swedish boys also have a smaller BMI range, on average, than their American counterparts, which just makes things more confusing.
As a result, the research may be “cautiously extrapolated to a heavier and more heterogeneous population of US adolescent boys,” according to Dr. Vanessa Curtis and Dr. David Allen — from the University of Iowa and the University of Wisconsin, respectively. The key word being cautiously, as other factors such as nutrition, involvement in sports, and stressors were not taken into account.
Regardless, it looks like boys are becoming men at earlier ages — a frightening prospect for any parent of a teenage boy. The grocery bill (and the gaming console budget) might look a lot more imposing for parents of the 21st century.