How does a child’s body know when it’s time to mature and to start puberty? The parents’ height may hold the key to an explanation, according to a new Israeli study.
While there is a wide range of normal ages for puberty to kick in, scientists have had little success validating the most prevalent current assumption: that genetics plays a major role in determining the time of the onset.
But research affirming a different hypothesis has been conducted by Dr. Yehuda Limony and Prof. Michael Friger of Ben-Gurion University of the Negev (BGU) in Beersheba, in collaboration with Slawomir Koziel of the Polish Academy of Sciences in Wroclaw, Poland. The paper was published last month in the PLOS ONE journal.
The researchers found that the age at which a child begins to show signs of pubic hair, and for girls, breasts and menstruation, is linked to the child’s “height gap,” or the gap between the child’s height percentile relative to their age group and their expected final adult height (as measured by the parents’ percentiles of height), according to a statement from BGU.
“Our findings mean that the age a child reaches puberty is not set genetically,” Limony said. “Rather, the body responds to the child’s individual growth needs. When a ‘tall’ child appears headed for an adult height that would make them much taller than their parents, they may hit puberty earlier than their peers in order to stop the growth process earlier and ensure that their final (adult) height is in the ‘target’ range.
“The opposite is also true: ‘Short’ children (as compared to their parents) do not hit puberty until later than the population average because the body is giving the child extra time to grow, in order to reach his or her parents’ height.”
The study analyzed data from two separate groups of Polish and Israeli children. The Polish group comprised 335 children — 162 girls and 173 boys — from nine randomly selected elementary schools in Wroclaw. They were followed prospectively at annual intervals from age 8 until age 18 (boys) or age 17 (girls) from 1961 to 1972.
The Israeli group comprised 170 children — 60 girls and 110 boys — who had been referred to an endocrinology clinic in southern Israel between 2004 and 2015 for having either a normal but below average stature, a short stature, an early puberty or a late puberty. The children and their parents were measured using a wall-mounted stadiometer, and the children were then measured periodically over a period of 18 months.
“A child who hits puberty earlier than their peers, but at a time that is consistent with this height gap, should be considered ‘healthy,’ or at least less suspected as having a pathological precocious puberty,” Limony said, adding that the research could change the way health officials worldwide determine whether the timing of the beginning of puberty in individuals is problematic or not.
“The determination of whether timing for puberty should be considered physiological or pathological should not be made by norms within the population, but rather determined by personal considerations for each child in line with our model,” he said. “We believe that using this model, or similar ones, will reduce the use of unnecessary diagnostic procedures while also explaining the emergence of early- or late-onset puberty.”