Association between duration of breast feeding* and selected socioeconomic variables, Boyd-Orr cohort, UK
| 2 weeks to <2 months | ≥2 to 6 months | ≥6 to 12 months | Over 12 months | |
|---|---|---|---|---|
| Percentages (in parentheses) relate to row totals. | ||||
| *Excluding duration unknown. | ||||
| †Income (shillings; s) per head per week as recorded in original survey, but with the original last three groups collapsed into a single category. | ||||
| ‡Shillings and pence per head per week spent on food as recorded in original survey but with the original last three groups collapsed into a single category. | ||||
| §Assigned using the Registrar General’s 1931 classification of occupations from social class I (professional) to social class V (unskilled manual). | ||||
| Income group (%)† | ||||
| >20s | 16 (14.7) | 27 (24.8) | 60 (55.1) | 6 (5.5) |
| >15–20s | 9 (10.3) | 22 (25.3) | 49 (56.3) | 7 (8.1) |
| 10–15s | 15 (4.5) | 105 (31.3) | 178 (53.0) | 38 (11.3) |
| <10s | 85 (6.5) | 302 (23.2) | 745 (57.3) | 168 (12.9) |
| χ2 test for heterogeneity (9 df) | p=0.001 | |||
| Expenditure group (%)‡ | ||||
| >9s | 18 (13.2) | 34 (25.0) | 75 (55.2) | 9 (6.6) |
| 7s–8s 11.75d | 9 (4.8) | 52 (27.8) | 105 (56.2) | 21 (11.2) |
| 5s–6s 11.75d | 46 (9.4) | 138 (28.2) | 245 (50.0) | 61 (12.5) |
| ≤4s 11.75d | 52 (5.1) | 237 (23.1) | 608 (59.2) | 130 (12.7) |
| χ2 test for heterogeneity (9 df) | p<0.0001 | |||
| Social class (%)§ | ||||
| I/II | 12 (10.3) | 37 (31.9) | 61 (52.6) | 6 (5.2) |
| III | 18 (5.4) | 115 (34.2) | 182 (54.2) | 21 (6.3) |
| IV | 32 (8.2) | 93 (23.9) | 207 (53.1) | 58 (14.9) |
| V | 16 (5.8) | 65 (23.6) | 160 (58.2) | 34 (12.4) |
| Unemployed | 46 (8.0) | 116 (20.1) | 336 (58.2) | 79 (13.7) |
| χ2 test for heterogeneity (12 df) | p<0.0001 | |||