Dataset Information

Secular Trends in Pubertal Growth Acceleration in Swedish Boys Born From 1947 to 1996.

ABSTRACT:

Importance

A secular trend for earlier menarcheal age has been established in girls but there are few studies of pubertal timing for boys.

Objective

To determine if there is a secular trend for earlier pubertal timing among boys.

Design, setting, and participants

For this population-based retrospective cohort study conducted in Gothenburg, Sweden, we collected heights and weights from school health records for boys born consecutively from January 1 and onwards in 1947 and every 5 years from 1951 to 1996 (n = 375 for each birth cohort from 1947-1991, n = 340 for the birth cohort in 1996, and n = 4090 for the total cohort). We estimated age at the peak height velocity (PHV), the maximum growth velocity during puberty, and childhood body mass index (BMI) at age 8 years for all study participants. The data were analyzed during 2018 and 2019. Boys were eligible if they had a complete personal identity number and data to calculate their age at PHV and childhood BMI. Approximately 2.4% of the original study population was excluded because they lacked a personal identity number, and in the remaining study population, 4090 (69%) had sufficient data to calculate childhood BMI and age at PHV.

Exposures

The exposure was birth year and a potential confounding factor was childhood BMI.

Main outcomes and measures

The outcome was age at PHV.

Results

Of the 4090 participants, most were white and the mean (SD) age at PHV was 13.9 (1.1) years. A linear regression model revealed a significant association between year of birth and age at PHV. Age at PHV was 1.5 months earlier for every decade increase in birth year (95% CI, -1.72 to -1.19; P < .001). After adjusting for childhood BMI, age at PHV was 1.2 months earlier per decade increase in birth year (95% CI, -1.41 to -0.89). All analyses were repeated in the subgroup of boys born in Sweden and with parents born in Sweden with similar results, indicating that the secular trend was not explained by demographic changes in the population between 1947 and 1996.

Conclusions and relevance

We provide evidence of a secular trend for earlier pubertal timing in boys that is partially explained by an increased childhood BMI, but other factors that are unknown contribute.

SUBMITTER: Ohlsson C

PROVIDER: S-EPMC6647355 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:ImportanceThe initial clinical sign of pubertal onset in girls is breast gland development (thelarche). Although numerous studies have used recalled age at menarche (first menstruation) to assess secular trends of pubertal timing, no systematic review has been conducted of secular trends of thelarche.ObjectivesTo systematically evaluate published data on pubertal timing based on age at thelarche and evaluate the change in pubertal onset in healthy girls around the world.Data sourcesA systematic literature search was performed in PubMed and Embase of all original peer-reviewed articles published in English before June 20, 2019.Study selectionIncluded studies used clinical assessment of breast development in healthy girls and used adequate statistical methods, including the reporting of SEs or CIs. The quality of the articles was evaluated by assessing study design, potential sources of bias, main characteristics of the study population, and methods of statistical analysis.Data extraction and synthesisIn accordance with PRISMA guidelines, all articles were assessed for eligibility independently by 2 authors. Weighted regression analysis was performed using a random-effects model.Main outcomes and measuresStudies examining age at thelarche (development of Tanner breast stage 2) in healthy girls.ResultsThe literature search resulted in a total of 3602 studies, of which 30 studies fulfilled the eligibility criteria. There was a secular trend in ages at thelarche according to race/ethnicity and geography. Overall, the age at thelarche decreased 0.24 years (95% CI, -0.44 to -0.04) (almost 3 months) per decade from 1977 to 2013 (P?=?.02).Conclusions and relevanceThe age at thelarche has decreased a mean of almost 3 months per decade from 1977 to 2013. A younger age at pubertal onset may change current diagnostic decision-making. The medical community needs current and relevant data to redefine "precocious puberty," because the traditional definition may be outdated, at least in some regions of the world.