Date Published: January 25, 2019
Publisher: Public Library of Science
Author(s): Yehuda Limony, Slawomir Koziel, Michael Friger, C. Mary Schooling.
The onset age of physiological puberty is greatly variable. This variability has been attributed to environmental factors and to genetic factors although a very little is explained by genome-wide associations studies. Previously, we reported the existence of an association between the onset age of puberty and final height. It is known that final height is associated with parental height (specifically, with the “target height”). We hypothesized that the variability of the onset age of puberty contributes to the attainment of a final height which is similar to the target height. We hypothesized that whenever a child’s height-percentile differs from the target height percentile (we called this difference the “height gap”), the onset of puberty is advanced or delayed so that they are closer or even equal at the end of pubertal growth. The association between height gap and onset age of puberty was investigated in the reported study.
The study is an observational retrospective study on growth during puberty in 170 Israeli (60 girls) and 335 Polish children (162 girls). Anthropometric measurements were analyzed by multivariable linear regression with the onset age of the pubertal growth spurt (PGS) as the dependent variable, and two independent variables “height gap” and body mass index (BMI)—both standardized.
The adjusted coefficient of determination (adj R2) between the onset age of the PGS and the two independent variables was 0.69 (Israeli girls), 0.50 (Israeli boys, BMI excluded), 0.25 (Polish girls) and 0.13 (Polish boys). A prediction model for the onset age of puberty is presented.
The association between the “height gap” and the onset age of puberty suggests that the variability of this age is part of the targeted process of statural growth. The proposed model may explain idiopathic cases of precocious and delayed puberty.
The onset age of physiologic puberty is greatly variable, and this variability has been attributed to genetic and environmental factors [1–3]. Although the early onset of puberty has been linked to high values of body mass index (BMI)) and tall stature in childhood [4–6], a model, which explains the physiologic variability of onset age of puberty, is still lacking.
We conducted an observational retrospective study on growth and puberty in two separate groups of Polish and Israeli children. The Polish group comprised 335 children (162 girls) from nine randomly selected Wroclaw elementary schools. They were followed prospectively at annual intervals from age 8 years until age 18 years (boys) and 17 years (girls) from 1961 to 1972 (The Wroclaw Growth Study) [11, 19–20].
Mean values of the onset age of the PGS, BMI (percentile and SDS), mid-parental height (SDS), pre-pubertal height (SDS) and the height gap are presented in Table 1.
This study was done on two groups of children which differed in their geographic locations and in the timeliness of data collection: the Israeli children were measured between the years 2004 and 2015 and the Polish children were measured between 1961 and 1972. Since the study tested a hypothesis which is related to the physiology of puberty, this difference between the two groups constitutes the study’s strength. Environmental influences on the onset age of puberty may change rapidly but physiologic factors are unlikely to change, if at all, during a few decades. In this study, we describe an association between the “height gap” and the onset age of puberty in two groups of children in whom height measurements were done longitudinally during two different periods in two different countries.