Table 2.
Estimated age of attainment for each of the motor milestones among children in the study population compared with the WHO reference population
| WHO growth standards reference*, median (IQR) age of attainment, months | WASH Benefits study children†, median (IQR) age of attainment, months | Age 7–9 months (N=282) | Age 9–11 months (N=1603) | Age 11–13 months (N=1989) | Age 13–15 months (N=843) | |
|---|---|---|---|---|---|---|
| Sitting without support | 5·9 (5·8–6·0) | ·· | 280 (99·6%) | 1588 (99·3%) | 1979 (99·5%) | 835 (99·3%) |
| Standing with assistance | 7·4 (6·6–8·4) | 8·7 (8·0–9·3) | 141 (50·5%) | 1320 (83·1%) | 1860 (94·5%) | 814 (97·4%) |
| Hands-and-knees crawling | 8·3 (8·2–8·4) | ·· | 162 (57·7%) | 1111 (69·5%) | 1504 (76·0%) | 672 (80·0%) |
| Walking with assistance | 9·0 (8·2–10·0) | 10·5 (9·1–11·3) | 29 (10·4%) | 739 (46·4%) | 1579 (80·3%) | 760 (91·1%) |
| Standing alone | 10·8 (9·7–12·0) | 11·9 (10·9–13·7) | 6 (2·1%) | 237 (14·9%) | 965 (48·9%) | 631 (75·8%) |
| Walking alone | 12·0 (11·0–13·0) | 13·0 (11·9–14·1) | 1 (0·4%) | 47 (2·9%) | 527 (26·7%) | 529 (63·3%) |
*
Published data from the WHO Multicentre Growth Reference Study.14
†
Estimated using non-parametric maximum likelihood estimator of cumulative probability of attainment. Median age could not be estimated for the sitting without support and hands-and-knees crawling milestones because >80% of children had already achieved this milestone before the assessment.