Growth patterns and the timing of stunting and non-stunting

Anthropometrics were measured in 522 of the 538 participants who attended the

During the study, there were 20,683 individual measurements performed: an average of 27 and maximum of 37 for each participant. The linear growth of the participants from birth until 15 years of age is described in Figure 6. The mean (SD) length/height of the boys was 51 cm (2.5) at one month, 100 cm (4.8) at five years and 154 cm (8.2) at 15 years of age. The respective figures for the girls were 50 cm (2.4), 99 cm (4.6) and 153 cm (5.8). The mean LAZ declined rapidly until two years of age, after which it reached the lowest point of -3.1 in the boys and -2.9 in the girls (Figure 6.). After two years of age there was an increase in the mean Z-score that continued until the age of 15 in girls, but decreased after ten years of age in boys. At 15 years of age, the mean HAZ was approximately -2.0 in boys and -1.3 in girls (Figure 6.).

In this study, it was demonstrated, that catch-up growth and transition from non-stunted to non-stunted status and vice versa throughout the follow-up period from infancy to 15 years of age may occur. To address the discussion about plausibility of catch-up growth in absolute height versus LAZ/HAZ, growth both in terms of absolute height gains and deficits measured in centimetres and changes in LAZ/HAZ was presented.

At one month of age, children were on average 3.5 cm shorter than the children in the WHO reference population. The deficit in absolute length and height increased until the children were four years old and remained at about 10–12 cm in both sexes. In girls, there was a slight catch-up after the age of 10, but a further decline in the boys (Figure 6.). The mean deficit in length was 9 cm for the girls and 15 cm for the boys at 15 years of age. Notable differences in the shape of the height trajectories were not found, neither in centimetres nor in z-scores between the children who, at the age of two, were moderately (> - 3 SD but ≤ - 2 SD) or severely (≤ - 3 SD) stunted, compared to those who were not stunted (>-2 SD). This applied to both sexes. The difference in the mean LAZ between the non-stunted and the severely stunted groups was highest at the age of two, at which point it was 2.9 Z-scores for boys and 2.4 for girls. At the age of 15, the respective differences narrowed to 1.3 and 0.9. In contrast, the difference in mean height deficit between the children who were not stunted and those who were severely stunted at two years of age increased throughout childhood in the boys and reached 10.7 cm at the age of 15. In girls, the difference in height deficit was at its largest at the age of nine (7.5 cm) and decreased to 7 cm at the age of 15 (Figure 6.).

Figure 6. Linear growth among boys (n = 412) and girls (n = 394) in LCSS cohort. The solid lines indicate HAZ scores, and the dashed lines refer to the mean deficits in centimetres compared to the reference population (14,15). The growth curves are LOWESS-smoothed.

The transition status in stunting between age intervals is shown in Figure 8. A stricter definition than simply crossing the -2 SD cut-off was used to define a transition between stunting and non-stunting status to eliminate the effect of possible measurement inaccuracies. The participants who were classified as remaining stunted had LAZ/HAZ measurements of < -2 SD at the first measurement and LAZ/HAZ measurements of < -1.8 SD at the second measurement. The ones who became non-stunted made the transition from LAZ/HAZ < -2 SD to LAZ/HAZ > -1.8. Those who remained non-stunted had a LAZ/HAZ of > -2 SD at the first measurement and > -2.2 SD at the second. Those who became stunted made the transition from an LAZ/HAZ of > - 2 SD to an LAZ/HAZ of < -2.2 SD. At between one and six months, 25.0% of the previously non-stunted infants became stunted and at between six and 12 months, 16.7%. The risk of stunting decreased along the age intervals.

The proportion (95% CI) of stunted children (< -2 SD) was 80% (95% CI 76.5–

83.5) when the children were two years old and declined to 37% (32.9–41.7) by the

-15-10-5 Mean deficit (cm)

-3-2-1Mean HAZ / LAZ

0 2 4 6 8 10 12 14 16

Age (years) Boys z-score Girls z-score

Boys deficit (cm) Girls deficit (cm)

became stunted was 21.3% (95% CI 17.5–25.1) between one and 60 months, 3.9%

(2.2–5.6) between 60 and 120 months and 9.1% (6.5–11.7) between 120 and 180 months. The respective figures for recovering from stunting were 9.2% (95% CI 6.6–11.9), 15.0% (11.9–18.2) and 9.1% (6.5–11.7). Of the children who were moderately or severely stunted at the age of two years, 84.7% (95% CI 79.4–90.0) and 58.9% (53.0–64.8) were classified as non-stunted at least once during the rest of the follow-up.

Figure 7. Participants shifting to a different status of stunting or remaining in the same status between age intervals. The numbers on the bars represent the percentages of stunted participants at each time point.

By the age of 15, only 9.0% (95% CI 5.4–12.6%) of the boys and 19.6% (14.5–

24.8%) of the girls had reached advanced puberty (Tanner Stages IV–V) as indicated by their pubic hair. There was a positive association between pubertal status and the absolute deficit in length when compared to the WHO reference population. For the adolescents in pubertal stage I at 15 years of age, the mean deficit in height was 21 cm for the boys and 13 cm for the girls. For those in pubertal stage V, the mean deficit was approximately 8 cm for both the boys and girls.

58% 69% 80% 83% 71% 58% 39% 37%

020406080100

Percentage of children

6 12 24 36 48 60 120 180

Age (Months)

Remain stunted Become stunted Recovered Remain non-stunted

5.3 Association between early development and later school