In the international study depicted here, the negative beta coefficients represent the decrease in blood pressure observed (per mmHg) for every unit increase in birth weight (kg). As depicted, most study sites showed a negative association, with the exception of the Nigerian population. However, given the wide confidence intervals, the findings are very weak. In analyses of ponderal index in the same study, a similarly weak inverse trend was noted for all countries except China which did not show an inverse trend.

The genetic diversity represented in the populations examined may contribute to the inconsistencies. Studies of black populations, for example, have, in particular, shown inconsistencies in the relationship between birth weight and blood pressure. It may also be possible that the inconsistencies in the literature are attributed to the influences of unmeasured or unexamined effect modifiers. Finally, childhood and the adolescent period may not be an optimal time for examining the fetal origins of disease hypothesis. For example, differences in the timing of growth spurts within and between study populations could add considerable "noise" to data.