Characteristics of pregnant women admitted to UK hospitals with SARS-CoV-2 related symptoms during periods in which the original wildtype, alpha variant, and delta variant were dominant
| Characteristic | Wildtype period (n=1387) | Alpha variant period (n=1613) | Delta variant period (n=1436) |
| Age (years) | |||
| <20 | 20 (1.4) | 18 (1.1) | 36 (2.5) |
| 20-34 | 953 (68.8) | 1137 (70.6) | 1015 (71.4) |
| ≥35 | 413 (29.8) | 456 (28.3) | 371 (26.1) |
| Missing data | 1 | 2 | 13 |
| Body mass index | |||
| Underweight (<18.5) | 21 (1.6) | 16 (1.0) | 21 (1.5) |
| Normal (18.5 to <25) | 439 (32.8) | 517 (33.6) | 434 (31.9) |
| Overweight (25 to <30) | 432 (32.3) | 454 (29.5) | 442 (32.4) |
| Obese (≥30) | 446 (33.3) | 553 (35.9) | 465 (34.2) |
| Missing data | 49 | 73 | 74 |
| Either woman or partner in paid work | 1106 (79.7) | 1210 (75.0) | 1017 (70.8) |
| Ethnic group | |||
| White | 675 (49.7) | 902 (57.3) | 965 (69.3) |
| Asian | 409 (30.1) | 400 (25.4) | 208 (14.9) |
| Black | 173 (12.7) | 163 (10.4) | 128 (9.2) |
| Chinese/other | 71 (5.2) | 66 (4.2) | 59 (4.3) |
| Mixed | 31 (2.3) | 43 (2.7) | 32 (2.3) |
| Missing data | 28 | 39 | 44 |
| Current smoking | 97 (7.3) | 137 (8.7) | 168 (12.2) |
| Missing data | 62 | 42 | 55 |
| Pre-existing medical conditions | 165 (11.9) | 221 (13.7) | 194 (13.5) |
| Asthma | 91 (6.6) | 163 (10.1) | 149 (10.4) |
| Hypertension | 39 (2.8) | 30 (1.9) | 17 (1.2) |
| Cardiac disease | 20 (1.4) | 18 (1.1) | 15 (1.0) |
| Diabetes | 35 (2.5) | 27 (1.7) | 21 (1.5) |
| Gestational diabetes | 143 (10.3) | 187 (11.6) | 109 (7.6) |
| Multiparous | 828 (60.1) | 1065 (66.5) | 944 (67.0) |
| Missing | 9 | 12 | 26 |
| Multiple pregnancy | 36 (2.6) | 35 (2.2) | 35 (2.4) |
| Gestation at admission (weeks+days) | |||
| <22 | 147 (10.6) | 178 (11.2) | 130 (9.2) |
| 22-27+6 | 155 (11.2) | 214 (13.4) | 214 (15.2) |
| 28-33+6 | 295 (21.4) | 354 (22.2) | 341 (24.1) |
| 34-36+6 | 217 (15.7) | 258 (16.2) | 257 (18.2) |
| ≥37 | 567 (41.1) | 591 (37.1) | 473 (33.4) |
| Missing data | 6 | 18 | 24 |
Data are number (%) of women.