Population-based studies show a reduction in the median age of puberty in various countries
(IPCS/WHO, 2002). According to Teilmann et al (2002) at the turn of the 19th century
puberty started at the age of 17; then it shifted quickly to an earlier age. Data on pubertal
development in boys are limited due to a lack of marked indicators such as age of menarche
in girls (de Muinck Keizer-Schrama and Mul, 2001). The age of menarche decreased until the
1980s in most European countries; current mean ages vary between 12.5 and 13.1 years; these
are similar in the USA (12.9 in Caucasian, 12.2 in Afro-American girls). However, in Europe
the largest decrease was observed until the early 1980s. Thereafter, depending on the country,
only a small decrease (Netherlands, Germany, Bulgaria), no significant change (Belgium,
Norway) or even an increase (Italy, Croatia) in age of menarche have been observed (de
Muinck Keizer-Schrama and Mul, 2001).
Among the factors considered responsible for the trend of earlier onset of puberty are
improved general health, socio-economic status, and nutrition (Teilmann et al, 2002).
The relationship between increased body mass index and earlier onset of puberty in both
white and black girls in the US observed by Kaplowitz et al (2001) supports the assumption
that obesity is an important contributing factor to the earlier onset of puberty in girls.
Prospective (mother-) child cohorts provide one of the most important epidemiological tools
with which to study the effect of exposure from the time of conception and during childhood
on various health outcomes such as development of puberty.
Most valuable would be a study ongoing already for at least 15-20 years during which
detailed information on the development of puberty, repeated standardized anthropometric
measurements including markers of sexual development at defined ages had already been
obtained as well as information on dietary habits - both qualitative and quantitative -
representative for defined periods during childhood and early adolescence.
In addition, available blood or urine samples, if taken and stored appropriately, could be used
for the determination of hormonal (metabolite) concentrations or profiles as well as, if
specific hypotheses exist, for the assessment of levels of compounds potentially affecting
puberty such as phytoestrogens. The usefulness of existing samples for such analyses needs to
The emotional discussion of a possible earlier onset of puberty mainly focuses on impacts of
chemical substances. Impacts of other factors keep disregarded. Through the consideration of
the potentially most relevant factors, especially nutrition, the results may be used in the
political discussion on endocrine disruptors. Results are needed soon; and the evaluation of
already - in a standardized manner - collected data would represent a unique opportunity to
contribute to the ongoing discussion in a timely manner.
- Recent trends in puberty onset and development
- Relationship between childhood growth patterns and puberty development
- Interaction between nutritional factors during childhood and puberty
- Impact of hormone levels during childhood on puberty
- Impact of nutrition during puberty on its further development (potential nutritional focus
Proposals submitted for consideration should describe in detail the existing cohort and data
obtained so far and address the objectives mentioned in a step-wise approach with clear
hypotheses to be assessed. A thorough plan of investigation is needed, including a clearly
defined milestone plan which
- identifies all critical decision points in the research programme;
- addresses the power of the study with regard to the primary hypotheses to be assessed; gives a detailed breakdown of costs.