Table 1.
Characteristics (% or Mean (SD)) of 13,824 PROBIT Children Recruited in 1996–1997 and Followed Up at Age 6.5 Years by Gestational Age
| 37 Weeks (n = 469) | 38 Weeks (n = 2,100) | 39 Weeks (n = 4,194) | 40 Weeks (n = 5,956) | 41 Weeks (n = 924) | 42 Weeks (n = 171) | 43 Weeks (n = 10) | All (n = 13,824) | |
| Birth weight, kg | 3.08 (0.37) | 3.27 (0.39) | 3.41 (0.39) | 3.51 (0.41) | 3.64 (0.43) | 3.71 (0.49) | 3.82 (0.60) | 3.44 (0.42) |
| Boys, % | 54.4 | 53.8 | 50.8 | 51.7 | 49.5 | 52.0 | 60.0 | 51.7 |
| Maternal age, % | ||||||||
| <20 years | 16.8 | 15.1 | 13.4 | 13.5 | 13.3 | 13.5 | 20.0 | 13.8 |
| 20–34 years | 77.2 | 80.2 | 82.2 | 82.4 | 84.1 | 83.0 | 80.0 | 82.0 |
| ≥35 years | 6.0 | 4.7 | 4.4 | 4.1 | 2.6 | 3.5 | 0.0 | 4.2 |
| Maternal height, cm | 164.3 (5.3) | 164.0 (5.6) | 164.4 (5.6) | 164.4 (5.6) | 164.7 (6.0) | 164.3 (5.6) | 166.9 (7.9) | 164.4 (5.6) |
| Missing, % | 5.2 | 15.5 | 25.8 | 46.4 | 5.8 | 1.3 | 0.0 | 0.1 |
| Smoking during pregnancy, % | 3.2 | 2.1 | 1.7 | 2.1 | 3.1 | 2.3 | 0.0 | 2.1 |
| Drinking during pregnancy, % | 2.8 | 2.1 | 2.3 | 2.1 | 2.6 | 2.3 | 0.0 | 2.2 |
| Marital status, % | ||||||||
| Registered marriage | 85.5 | 87.2 | 88.8 | 89.9 | 90.4 | 91.8 | 70.0 | 89.1 |
| Unregistered marriage | 9.0 | 7.8 | 6.9 | 6.7 | 6.5 | 6.4 | 20.0 | 7.0 |
| Unmarried | 5.5 | 5.0 | 4.2 | 3.3 | 3.1 | 1.7 | 10.0 | 3.9 |
| No. of children at home, % | ||||||||
| 1 child | 59.5 | 59.0 | 56.5 | 55.4 | 59.1 | 58.5 | 70.0 | 56.7 |
| 2 children | 28.8 | 33.6 | 35.9 | 35.3 | 32.5 | 26.9 | 20.0 | 34.7 |
| 3 children | 11.7 | 7.4 | 7.6 | 9.3 | 8.4 | 14.6 | 10.0 | 8.6 |
| Maternal education, % | ||||||||
| Less than secondary | 4.5 | 3.8 | 3.5 | 3.7 | 3.4 | 4.7 | 0.0 | 3.7 |
| Secondary | 36.0 | 31.8 | 31.1 | 32.6 | 30.0 | 36.3 | 50.0 | 32.0 |
| Partial university | 47.1 | 51.6 | 52.2 | 50.1 | 53.7 | 49.7 | 20.0 | 51.1 |
| University | 12.4 | 12.8 | 13.2 | 13.6 | 12.9 | 9.3 | 30.0 | 13.2 |
| Maternal occupation, % | ||||||||
| Manual | 29.0 | 22.9 | 26.8 | 29.4 | 31.1 | 36.8 | 30.0 | 27.8 |
| Service | 36.9 | 46.7 | 44.8 | 42.8 | 41.3 | 33.3 | 50.0 | 43.6 |
| Farmer | 7.5 | 5.9 | 5.8 | 6.0 | 4.3 | 8.2 | 10.0 | 5.9 |
| Pupil | 2.3 | 1.2 | 1.1 | 1.1 | 0.6 | 0.0 | 0.0 | 1.1 |
| Student | 1.9 | 2.2 | 2.0 | 2.0 | 1.8 | 2.9 | 0.0 | 2.0 |
| Housewife | 13.4 | 12.3 | 11.4 | 11.0 | 12.3 | 7.0 | 0.0 | 11.4 |
| Unemployed | 9.0 | 8.8 | 8.0 | 7.7 | 8.4 | 11.7 | 10.0 | 8.1 |
| Paternal education, % | ||||||||
| Less than secondary | 3.4 | 2.1 | 2.3 | 2.2 | 2.5 | 1.7 | 10.0 | 2.4 |
| Secondary | 40.7 | 32.2 | 34.1 | 38.3 | 35.7 | 39.8 | 40.0 | 37.2 |
| Partial university | 44.7 | 50.2 | 47.1 | 43.6 | 47.6 | 45.0 | 30.0 | 47.5 |
| University | 11.2 | 11.0 | 13.2 | 12.9 | 12.3 | 12.3 | 10.0 | 12.9 |
| Missing | 0.0 | 4.4 | 3.8 | 2.9 | 1.8 | 1.2 | 10.0 | 3.4 |
| Paternal occupation, % | ||||||||
| Manual | 48.6 | 40.9 | 44.2 | 45.9 | 48.0 | 49.1 | 50.0 | 44.9 |
| Service | 20.0 | 30.7 | 29.5 | 27.2 | 26.1 | 24.6 | 20.0 | 28.0 |
| Farmer | 11.5 | 9.0 | 8.6 | 10.1 | 8.2 | 12.9 | 0.0 | 9.4 |
| Pupil | 0.2 | 0.2 | 0.2 | 0.2 | 0.3 | 0.0 | 0.0 | 0.2 |
| Student | 0.6 | 0.9 | 0.9 | 1.0 | 0.8 | 0.0 | 0.0 | 1.0 |
| Unemployed | 13.6 | 13.2 | 12.0 | 12.2 | 13.2 | 11.1 | 20.0 | 12.4 |
| Unknown | 5.3 | 5.0 | 4.5 | 3.5 | 3.4 | 2.3 | 10.0 | 4.1 |
Abbreviations: PROBIT, Promotion of Breastfeeding Intervention Trial; SD, standard deviation.