Table 2 presents the correlation matrix for weight and length/ height gains. When expressed as z-scores, unconditional weight gain in a given age range tended to be inversely correlated to later weight gains; the same applied to length/height gain. Also, weight gain was positively correlated to length/height gain in the same age range. The use of conditional weights effectively removed the correlation between gains in successive periods with coefﬁcients being equal to zero. Conditional weight in any period, and to a lesser extent conditional height, were associated with higher BMI at 14e15 years. For adolescent height, the associations with conditional weight were signiﬁcant but weaker than those for conditional height. Table 3 shows that early (0e6 months) and late (12e48 months) weight gains were positively associated with systolic blood pressure, whereas gains from 6e12 months were not. This was observed in the crude and confounder-adjusted analyses. Further adjustment for adolescent height and BMI must be interpreted with caution because these variables are likely part of the causal chain between early growth and adolescent outcomes. In these analyses, weight gain from 6e12 months became inversely associated with systolic blood pressure. Results were similar for diastolic pressure (data not shown). BMI and the sum of skin folds were positively associated with weight gain in all periods; the only exception is the lack of correlation with the sum of skin folds when potential mediating variables (adolescent BMI and height) are adjusted for. There were no signiﬁcant associations with the skin fold ratio outcome in the adjusted models. Results for length/height gain (table 4) show that, after adjustment for confounders, late gains tend to be associated with all outcomes except subscapular/triceps ratio but not early gains. Patterns were not clear-cut after adjustment for adoles- cent BMI and height, which suggest that these variables mediate the effect of childhood height gain on adolescent outcomes. There were not signiﬁcant associations with the skin fold ratio in the adjusted models. Table 5 repeats the confounder-adjusted analyses (model 1 in tables 3 and 4) with further adjustment of weight gain for Maternal, child and adolescent health length/height gain and vice versa. Weight gains in all periods tended to remain positively associated with all outcomes except for the skin fold ratio. In marked contrast to weight gain, associations between length gain and both obesity outcomes were mostly negative particularly for the body composition outcomes. Further adjustment for height at 14e15 years did not change the direction or signiﬁcance of the associations (data not shown). All the analyses described above were repeated using as explanatory variables the crude, or unconditional weight and height gains in each period, rather than conditional analyses. Although as expected the magnitude of the coefﬁcients were different in the two sets of analyses, the ﬁndings were very similar in terms of direction and statistical signiﬁcance (data not shown). DISCUSSION 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 adult- hood.25 26 In our length-adjusted analyses, putting on weight rapidly from 0e6 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 Table 2 Pearson correlation coefﬁcients among infancy and childhood exposures and with BMI and height at 14e15 years Absolute (z-score) gains Conditional gains Weight gain Length/height gain Weight gain Length/height gain BMI 0e6 mo 6e12 mo 12e48 mo 0e6 mo 6e12 mo 12e48 mo 0e6 mo 6e12 mo 12e48 mo 0e6 mo 6e12 mo 12e48 mo 14e15 y Height 0.15** 0.10** 0.03 0.63** 0.02 0.00 0.10** 0.32** 0.02 0.19** 0.03 0.12** 0.49** 0.04 0.28** z-scores Weight 0e6 mo 6e12 mo 12e48 mo Length/height 0e6 mo 6e12 mo 12e48 mo Conditional Weight 0e6 mo 6e12 mo 12e48 mo Length/height 0e6 mo 6e12 mo 12e48 mo 1993 Pelotas Birth Cohort, Brazil, 2008. *p-value between 0.001 and 0.05; **p-value <0.001. BMI, body mass index; mo, months. J Epidemiol Community Health 2012;66:149e154. doi:10.1136/jech.2010.124842 0.81** 0.30** 0.25** 0.53** 0.02 0.16** 0.00 0.94** 0.13** 0.09** 0.31** 0.03 0.00 0.00 0.00 0.93** 0.10** 0.01 0.42** 0.00 0.00 0.44** 0.11** 0.07* 0.85** 0.32** 0.13** 0.63** 0.11** 0.13** 0.18** 0.28** 0.04 0.00 0.93** 0.41** 0.20** 0.36** 0.06* 0.00 0.01 0.19** 0.49** 0.00 0.00 0.84** 0.00 0.20** 0.55** 0.00 0.00 0.12* 0.04 0.02 0.02 0.28** 0.15** 0.04 0.01 0.06 0.21** 0.03 0.08 0.24** 0.30** 0.12* 0.17** 0.42** 0.26** 0.08* 0.43** 0.06* 0.25** 0.16** 0.37** 151