Table 1 Sample characteristics and distribution of variables included in regression models across levels of pre-pregnancy BMI (N = 7564)
Variables | Total N (%) | Pre-Pregnancy Body Mass Index | P-value (Χ2) | ||||
|---|---|---|---|---|---|---|---|
Underweight N (%) | Normal weight N (%) | Overweight N (%) | Obese Class I N (%) | Obese Class II & III N (%) | |||
Total | 7564 (100.0%) | 473(5.5%) | 4897(66.0%) | 1502(19.5%) | 488(6.4%) | 204(2.6%) | |
Education | |||||||
None of these | 1465 (15.4%) | 163 (31.9%) | 873 (13.9%) | 305 (15.8%) | 85 (13.9%) | 39 (17.9%) | < 0.0001 |
GCSE/A level | 4260 (57.5%) | 244 (54.1%) | 2714 (56.2%) | 866 (59.5%) | 306 (64.9%) | 130 (64.1%) | |
Higher education | 1839 (27.1%) | 66 (14.0%) | 1310 (29.9%) | 331 (24.7%) | 97 (21.2%) | 35 (18.0%) | |
Marital status | |||||||
Couple | 4545 (60.9%) | 205 (38.7%) | 2934 (61.2%) | 946 (63.2%) | 330 (68.1%) | 130 (65.9%) | < 0.0001 |
Single | 3019 (39.1%) | 268 (61.3%) | 1963 (38.8%) | 556 (36.8%) | 158 (31.9%) | 74 (34.1%) | |
OECD equivalised income quintile | |||||||
1st (lowest) | 1570 (16.5%) | 185 (34.92%) | 979 (15.6%) | 294 (19.6%) | 73 (15.0%) | 41 (16.4%) | < 0.0001 |
2nd | 1605 (18.4%) | 138 (27.28%) | 918 (16.4%) | 347 (23.1%) | 141 (28.9%) | 62 (28.1%) | |
3rd | 1473 (20.4%) | 70 (18.25%) | 944 (19.8%) | 309 (20.6%) | 107 (22.0%) | 43 (22.1%) | |
4th | 1440 (21.2%) | 37 (7.69%) | 964 (19.7%) | 300 (20.0%) | 100 (20.5%) | 39 (22.4%) | |
5th (highest) | 1476 (23.5%) | 43 (11.33%) | 1092 (26.5%) | 252 (16.8%) | 67 (13.7%) | 22 (11.0%) | |
Ethnicity | |||||||
White | 6259 (90.1%) | 340 (83.2%) | 4137 (91.2%) | 1208 (88.7%) | 397 (88.4%) | 177 (92.7%) | < 0.0001 |
Mixed/Other | 249 (2.5%) | 28 (3.7%) | 157 (2.4%) | 45 (2.1%) | 15 (3.0%) | 4 (1.4%) | |
Indian/ Pakistani/Bangladeshi | 794 (5.2%) | 88 (9.7%) | 471 (4.8%) | 176 (6.2%) | 45 (4.4%) | 14 (2.9%) | |
Black Caribbean or Black African | 262 (2.2%) | 17 (3.4%) | 132 (1.6%) | 73 (3.0%) | 31 (4.2%) | 9 (3.0%) | |
Government Office Region* | |||||||
North | 2345 (29.7%) | 158 (32.5%) | 1523 (29.8%) | 460 (29.4%) | 139 (27.9%) | 65 (28.9%) | 0.40 |
Midlands & East | 2391 (30.9%) | 138 (27.2%) | 1505 (30.3%) | 504 (32.0%) | 171 (33.9%) | 73 (30.9%) | |
London | 1213 (13.8%) | 90 (16.2%) | 793 (13.9%) | 231 (13.7%) | 77 (13.4%) | 22 (13.8%) | |
South | 1615 (25.6%) | 87 (24.1%) | 1076 (26.0%) | 307 (24.9%) | 101 (24.8%) | 44 (26.5%) | |
Premature | |||||||
No | 7055 (93.4%) | 428 (90.4%) | 4575 (93.7%) | 1419 (94.2%) | 457 (93.4%) | 176 (85.7%) | 0.0002 |
Yes | 509 (6.6%) | 45 (9.6%) | 322 (6.3%) | 83 (5.8%) | 31 (6.6%) | 28 (14.3%) | |
Parity | |||||||
Primiparae | 7291 (96.5%) | 444 (93.6%) | 4747 (97.0%) | 1445 (96.0%) | 466 (95.5%) | 189 (93.2%) | 0.001 |
Multiparae | 273 (3.5%) | 29 (6.4%) | 150 (3.0%) | 57 (4.0%) | 22 (4.5%) | 15 (6.8%) | |
Notional cost of treatment (UK£) | |||||||
1–250 | 11 (0.2%) | 1 (0.2%) | 5 (0.2%) | 3 (0.2%) | 2 (0.6%) | 0 (0.00%) | < 0.0001 |
250–500 | 1126 (14.9%) | 86 (17.7%) | 747 (15.7%) | 218 (14.1%) | 58 (10.9%) | 17 (9.2%) | |
500–750 | 3615 (47.7%) | 238 (51.8%) | 2.394 (48.5%) | 695 (47.3%) | 198 (39.9%) | 90 (42.5%) | |
750–1000 | 1701 (22.7%) | 93 (18.7%) | 1108 (22.8%) | 331 (22.4%) | 126 (27.0%) | 43 (20.2%) | |
1000–1250 | 656 (8.8%) | 28 (5.9%) | 385 (8.0%) | 151 (9.8%) | 59 (12.4%) | 33 (18.6%) | |
1250–1500 | 221 (2.8%) | 12 (2.2%) | 126 (2.5%) | 54 (3.3%) | 26 (5.5%) | 3 (1.1%) | |
1500–1750 | 85 (1.1%) | 5 (1.1%) | 46 (0.9%) | 21 (1.3%) | 6 (1.2%) | 7 (3.1%) | |
1750–2000 | 43 (0.6%) | 2 (0.5%) | 21 (0.4%) | 12 (0.8%) | 3 (0.5%) | 5 (3.0%) | |
2000 or over | 106 (1.2%) | 8 (1.8%) | 65 (1.2%) | 17 (0.9%) | 10 (2.0%) | 6 (2.4%) | |
Mean (SE) | Mean (SE) | Mean (SE) | Mean (SE) | Mean (SE) | Mean (SE) | Mean (SD) | |
Maternal age (years) | 28.8 (0.2) | 25.0 (0.3) | 28.8 (0.2) | 29.4 (0.2) | 29.3 (0.3) | 29.8 (0.4) | < 0.0001 |
Length of stay (days) | 2.8 (0.1) | 2.6 (0.2) | 2.7 (0.1) | 2.9 (0.1) | 3.4 (0.2) | 3.8 (0.3) | < 0.0001 |