| Characteristics | 2002 (N = 3,450) | 2007 (N = 6,307) | 2012 (N = 6,365) |
| SOCIODEMOGRAPHIC | |||
| Age, y | |||
| 15–19 | 55 (1.6) | 123 (1.9) | 135 (2.1) |
| 20–24 | 515 (14.9) | 974 (15.4) | 854 (13.4) |
| 25–29 | 884 (25.6) | 1654 (26.2) | 1669 (26.2) |
| ≥ 30 | 1997 (57.9) | 3556 (56.4) | 3707 (58.2) |
| Place of Residence | |||
| Urban | 2705 (78.4) | 5298 (84.0) | 5198 (81.7) |
| Rural | 746 (21.6) | 1009 (16.0) | 1167 (18.3) |
| Geographic Region | |||
| Central | 2191 (63.5) | 3908 (62.0) | 3935 (61.8) |
| North | 930 (27.0) | 1844 (29.2) | 1821 (28.6) |
| South | 329 (9.5) | 555 (8.8) | 609 (9.6) |
| Mother's Education | |||
| No education | 128 (3.7) | 147 (2.3) | 114 (1.8) |
| Primary | 277 (8.0) | 337 (5.3) | 373 (5.9) |
| Secondary | 2087 (60.5) | 3885 (61.6) | 3825 (60.1) |
| Higher | 959 (27.8) | 1939 (30.7) | 2053 (32.2) |
| Husband's Education | |||
| No education | 65 (1.9) | 91 (1.5) | 59 (0.9) |
| Primary | 371 (10.8) | 665 (10.6) | 661 (10.4) |
| Secondary | 1980 (57.4) | 3793 (60.3) | 4000 (62.8) |
| Higher | 1034 (30.0) | 1745 (27.7) | 1645 (25.8) |
| Missing (Do not know) | 12 (0.2) | 1 (0.02) | |
| Employment | |||
| Unemployed | 3101 (89.9) | 5526 (87.6) | 5381 (84.5) |
| Employed | 350 (10.1) | 781 (12.4) | 985 (15.5) |
| Place of Delivery | |||
| Public sector | 2229 (64.6) | 4036 (64.0) | 4230 (66.5) |
| Private sector | 1221 (35.4) | 2271 (36.0) | 2135 (33.5) |
| Wealth Index | |||
| Poorest | 786 (22.8) | 1462 (23.2) | 1313 (20.6) |
| Poorer | 881 (25.5) | 1475 (23.4) | 1365 (21.4) |
| Middle | 740 (21.4) | 1368 (21.7) | 1437 (22.6) |
| Richer | 594 (17.2) | 1131 (17.9) | 1291 (20.3) |
| Richest | 450 (13.0) | 872 (13.8) | 960 (15.1) |
| OBSTETRIC | |||
| Age at First Birth, y | |||
| 12–18 | 687 (19.9) | 1110 (17.6) | 917 (14.4) |
| 19–24 | 2010 (58.3) | 3661 (58.1) | 3747 (58.9) |
| 25–30 | 645 (18.7) | 1289 (20.4) | 1369 (21.5) |
| > 30 | 107 (3.1) | 246 (3.9) | 332 (5.2) |
| Parity in Last 5 Years | |||
| 1 | 1881 (54.5) | 3531 (56.0) | 3733 (58.6) |
| 2 | 1263 (36.6) | 2254 (35.7) | 2182 (34.3) |
| ≥ 3 | 307 (8.9) | 522 (8.3) | 451 (7.1) |
| Birth Weight, g | |||
| Normal (2500–3999) | 2618 (75.9) | 4916 (77.9) | 4907 (77.1) |
| Low or High (< 2500 or ≥ 4000) | 832 (24.1) | 1391 (22.1) | 1458 (22.9) |
| Birth Multiplicity | |||
| Singleton birth | 3371 (97.7) | 6185 (98.1) | 6225 (97.8) |
| Multiple birth | 80 (2.3) | 123 (1.9) | 140 (2.2) |
All data are reported as No. (%).