Our findings suggest that early weight gain increases adolescent blood pressure and fatness, whereas early length/height gains are not associated with higher blood pressure and seem to protect against overweight and fatness in adolescents. These results emerged when length/height gain and weight gain were adjusted for one another. The finding that the effects of weight and height gains seem to go in opposite directions is of great interest for public health.
Blood pressure is a challenging outcome for studies of the long-term consequences of early growth patterns because of its strong correlation with adult size.14 24
Using unconditional methods, previous studies reported that early weight gain was associated with higher blood pressure in adolescence and adulthood.25 26
In our length-adjusted analyses, putting on weight rapidly from 0–6 months was associated with higher blood pressure in adolescence, whereas later weight gain was not. A previous analysis of five cohorts in low and middle-income countries found that conditional weight at 12 months was positively associated with adult mean blood pressure and pre-hypertension in the confounder-adjusted analyses, but the associations were no longer significant after adjustment for adult height.14
Both BMI—which comprises fat and lean mass—and the sum of skin folds—which represents fat mass only—were positively associated with early weight gain. The regression coefficients suggest that weight gain from 12–48 months had a larger effect than earlier gains. It is reassuring that results on BMI and sum of skin folds are very consistent as these are two independent measures of obesity. A previous analysis of a subsample of 9-year-olds from our cohort showed that while early weight gain was related to lean mass assessed through isotope dilution, later weight gain was associated with fat mass.27
Also using BMI and skin folds, Stettler and colleagues found that rapid weight gain during early infancy was associated with obesity in older children and young adults,12
and suggested that the first week of life was critical for BMI development.13
These studies did not report on the effects of height gain nor used conditional growth modelling.
Length gain from 0–6 months, when adjusted for weight gain in the same period, did not appear to increase blood pressure—if anything it was associated with a borderline reduction (p=0.05) in systolic pressure. It was also associated with lower BMI and possibly with reduced skin folds. Length/height gains from 6–12 and 12–48 months were not associated with blood pressure, but showed negative associations with BMI and skin folds (not all of which were statistically significant), which suggest that putting on length/height without excessive weight gain is beneficial for body composition development.
Central deposition of fat can be measured both as waist circumference (alone or as a ratio to hip/thigh circumference) and as subscapular-to-triceps skin fold ratios. Both measures have been linked to glucose intolerance, hypertension and coronary heart disease.28–32
In our adjusted analyses, the skin fold ratio was not associated with early weight or height gains. This contradicts the findings of some studies,33 34
although there is no consensus on such observations.35
In some populations—for example in India—central fat deposition is already evident in infants.36
By adjusting early growth variables for adolescent BMI or height (model 2 in and ), we addressed the question of to what extent the effects of early weight and height gains on later outcomes may be channelled through adolescent size—which itself is partly a result of early growth patterns. For example, putting on weight rapidly in early life leads to larger BMI and height in adolescence, and early linear growth is also associated with adolescent height and to a lesser extent with adolescent BMI (). In our view, the most important results from the public health perspective are those unadjusted for adolescent size (eg, model 1 in and , and the models shown in ) because these address what might be expected from early interventions.
The present study is, to our knowledge, the first attempt to investigate long-term outcomes while mutually adjusting the effects of early weight and length/height gains. Also, by using the conditional method, we eliminated the correlation between growth variables in subsequent age ranges.15 16
A limitation of our cohort is the lack of measurements at the critical age of 2 years, which is widely regarded at the upper limit of the window of opportunity for preventing undernutrition.7 37
In low and middle-income countries, paediatric practice has included promoting rapid weight gain to prevent undernutrition and its harmful consequences.38
This is highly justified in societies where undernutrition is responsible for a large proportion of the burden of disease,39
but in face of the nutrition transition there may be detrimental long-term consequences of rapid weight gain.7
Nevertheless, it has been proposed that in such societies, the benefits of rapid weight gain in the first 2 years regarding short-term morbidity and mortality outcomes, as well as long-term human capital outcomes, far outweigh its potential contribution to complex chronic diseases in adulthood.7
Our findings suggest a new dimension to this debate, mainly that the promotion of rapid length/height gain without excessive weight gain may be beneficial for long-term outcomes. If our results are confirmed by other studies, it will be necessary to reassess the results of existing nutrition intervention studies to identify suitable strategies to achieve this growth pattern. Finally, our findings strongly support the need to monitor infant and child length/height in addition to the current practice of monitoring weight only.37
What is already known on this subject?
Although there is longstanding evidence of the short-term benefits of promoting rapid growth for young children in low-income settings, more recent studies suggest that early weight gain can also increase the risk of chronic diseases in adults. Supportive evidence on the benefits of rapid early weight gain in poor populations is provided by its positive association with human capital in adults. Rapid weight gain up to about the age of 2 years is more strongly associated with positive outcomes, whereas rapid weight gain in late childhood is associated with negative outcomes.
What this study adds?
Conditional weight gains in all different age ranges up to 4 years tended to be associated with higher blood pressure, BMI and skin folds. In marked contrast, rapid length/height gains tended to afford protection against most of these outcomes, particularly those related to body composition. These results emerged when length/height gain and weight gain were adjusted for one another.