Secular trends in growth: the narrowing of ethnic differences in stature

Summary Ethnic differences in growth patterns between countries have been observed even after controlling for nutrition, environment, and a range of other factors. The literature on markers of human growth patterns in different affluent populations was compared, with the aim of identifying similarities or differences that might be ascribed to nonenvironmental factors. To this end, the stature characteristics of different affluent child populations at various ages and stages (stature attained at 7 and 8 years of age; age at peak height velocity; peak height velocity) have been compared. The obvious flaw to this approach is that not all of them show maximal growth trajectories, because mean body size is still increasing for many, as the secular trend toward increasing body size has not ceased for many populations. Therefore, a review of the extent to which the same stature characteristics of populations of differing ethnicities have changed across time has been carried out, to determine the extent to which they might be approaching or attaining similar secular trend end‐points associated with the achievement of genetic potential for growth. The comparison of mean heights of 7‐year‐old boys from populations of industrialised countries and from the highest socio‐economic groups in developing countries, shows that the range of means for European and European‐origin populations is similar to those of African and African‐origin, and Latin‐American and Indo‐Mediterranean populations, but slightly higher than those of Asiatic populations. This supports the view that genetic potential for prepubertal growth may be similar for all groups examined in this way, apart from Asiatic populations. However, the secular trend toward increased body size has continued to take place among many populations, including affluent ones. The Asiatic populations observed since 1990 are much more similar in stature to their counterparts elsewhere in the world than they were prior to this date. A similar comparison among affluent adolescents shows Asiatic populations to have earlier onset of the pubertal growth spurt in stature than other major population typologies, but to have similar peak height velocities. The similarities in attained stature by mid‐childhood of children of most major population typologies, apart from the Asiatic one, suggests that an international growth reference could be used currently for all major population typologies apart from the Asiatic one. It is possible that they may also be applicable to preadolescent Asiatic populations, given the dramatic secular increase in childhood stature in recent decades, if they were to achieve the same statures for age as affluent populations elsewhere in the world. With respect to pubertal growth, international references may be applied to all major population typologies apart from the Asiatic one, as the earlier age of peak height velocity in these populations is unlikely to be due to differences in environmental quality.