Table 2. Monthly weight-for-age z-score and proportion of children underweight stratified by birth weight.
| Birth | Month 1 | Month 2 | Month 3 | Month 4 | Month 5 | Month 6 | Month 7 | Month 8 | Month 9 | Month 10 | Month 11 | Month 12 | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| All infants | |||||||||||||
| N | 1103 | 938 | 927 | 986 | 940 | 916 | 968 | 917 | 917 | 938 | 899 | 887 | 941 |
| Mean WAZ ±sd | -1.1 ±1.1 | -0.7 ±1.3 | -0.8 ±1.3 | -0.9 ±1.3 | -1.0 ±1.3 | -1.1 ±1.2 | -1.3 ±1.2 | -1.4 ±1.2 | -1.5 ±1.2 | -1.5 ±1.2 | -1.6 ±1.2 | -1.6 ±1.2 | -1.6 ±1.2 |
| WAZ<-2 (%) | 185 (17) | 134 (14) | 148 (16) | 159 (16) | 171 (18) | 176 (19) | 236 (24) | 278 (30) | 304 (33) | 304 (32) | 310 (34) | 298 (34) | 307.(33) |
| Normal birth weight | |||||||||||||
| N (%) # | 876 (79) | 745 (79) | 740 (80) | 786 (80) | 756 (80) | 739 (81) | 780 (81) | 741 (81) | 739 (81) | 762 (81) | 730 (81) | 724 (82) | 762 (81) |
| Mean WAZ ±sd | -0.7 ±0.7 | -0.3 ±1.0 | -0.5 ±1.1 | -0.6 ±1.1 | -0.7 ±1.1 | -0.9 ±1.1 | -1.1 ±1.1 | -1.2 ±1.1 | -1.3 ±1.2 | -1.4 ±1.2 | -1.4 ±1.1 | -1.4 ±1.1 | -1.4 ±1.1 |
| WAZ<-2 (%) | 0 | 35 (4.7) | 54 (7.3) | 73 (9.3) | 95 (13) | 109 (15) | 144 (18) | 183 (25) | 208 (28) | 209 (27) | 209 (29) | 203 (28) | 205 (27) |
| Low birth weight | |||||||||||||
| N (%) # | 227 (21) | 193 (21) | 187 (20) | 200 (20) | 184 (20) | 177 (19) | 188 (19) | 176 (19) | 178 (19) | 176 (19) | 169 (19) | 163 (18) | 179 (19) |
| Mean WAZ ±sd | -2.7 ±0.8 | -2.2 ±1.4 | -2.2 ±1.4 | -2.0 ±1.5 | -2.0 ±1.4 | -2.0 ±1.3 | -2.2 ±1.3 | -2.2 ±1.3 | -2.2 ±1.2 | -2.3 ±1.2 | -2.3 ±1.1 | -2.3 ±1.2 | -2.3 ±1.2 |
| WAZ<-2 (%) | 185 (82) | 99 (51) | 94 (50) | 86 (43) | 76 (41) | 67 (38) | 92 (49) | 95 (54) | 96 (54) | 95 (54) | 101 (60) | 95 (58) | 102 (57) |
| P-value * | <0.001 | <0.001 | <0.001 | <0.001 | <0.001 | <0.001 | <0.001 | <0.001 | <0.001 | <0.001 | <0.001 | <0.001 | <0.001 |
WAZ-Weight-for-age z-score, *the P-value is from the comparison of the means of WAZ between infants born LBW and normal birth weight using independent t-test, #-percentage of all infants in that follow-up visit.