Maternal characteristics associated with severe maternal morbidity
| Characteristic | Cases n=(%) N=1144 | Controls n=(%) N=2256 | Unadjusted OR (95% CI) | Adjusted* OR (95% CI) |
|---|---|---|---|---|
| Socioeconomic group | ||||
| Managerial/professional | 292 (25.5) | 567 (25.1) | 1.0 | 1.0 |
| Intermediate | 244 (21.3) | 482 (21.4) | 0.98 (0.80 to 1.21) | 1.17 (0.94 to 1.45) |
| Routine/manual | 273 (28.7) | 595 (26.4) | 0.89 (0.73 to 1.09) | 1.16 (0.93 to 1.45) |
| Unemployed | 142 (14.9) | 309 (13.7) | 0.89 (0.70 to 1.14) | 1.22 (0.92 to 1.61) |
| Missing | 193 (16.9) | 303 (13.4) | 1.24 (0.98 to 1.56) | 1.51 (1.18 to 1.94) |
| Ethnic group | ||||
| White | 827 (72.3) | 1796 (79.6) | 1.0 | 1.0 |
| Asian | 139 (12.2) | 197 (8.7) | 1.53 (1.22 to 1.93) | 1.57 (1.23 to 2.00) |
| Black | 108 (9.4) | 116 (5.1) | 2.02 (1.54 to 2.66) | 1.77 (1.32 to 2.36) |
| Other | 52 (4.6) | 69 (3.1) | 1.64 (1.13 to 2.37) | 1.50 (1.02 to 2.19) |
| Missing | 18 (1.6) | 78 (3.5) | 0.50 (0.30 to 0.84) | 0.51 (0.28 to 0.91) |
| Age | ||||
| <20 | 56 (4.9) | 139 (6.2) | 0.98 (0.70 to 1.39) | 1.08 (0.75 to 1.56) |
| 20–24 | 127 (11.1) | 449 (19.9) | 0.69 (0.54 to 0.89) | 0.71 (0.55 to 0.92) |
| 25–29 | 225 (19.7) | 549 (24.3) | 1.0 | 1.0 |
| 30–34 | 341 (29.8) | 622 (27.6) | 1.34 (1.09 to 1.64) | 1.33 (1.08 to 1.64) |
| ≥35 | 392 (34.3) | 479 (21.2) | 2.00 (1.63 to 2.45) | 1.98 (1.60 to 2.45) |
| Missing | 3 (0.3) | 18 (0.8) | 0.41 (0.12 to 1.39) | 2.66 (0.22 to 26.00) |
| Smoking status | ||||
| Non-smokers | 899 (78.6) | 1642 (72.8) | 1.0 | 1.0 |
| Smokers | 217 (19.0) | 553 (24.5) | 0.72 (0.60 to 0.86) | 0.89 (0.73 to 1.08) |
| Missing | 28 (2.5) | 61 (2.7) | 0.84 (0.53 to 1.32) | 0.95 (0.54 to 1.67) |
| BMI (kg/m2) | ||||
| Continuous (per kg/m2 increase in BMI) | 1.01 (1.00 to 1.03) | |||
| <25 | 513 (44.8) | 1121 (49.7) | 1.0 | 1.0 |
| 25–29.9 | 297 (26.0) | 545 (24.2) | 1.19 (1.00 to 1.42) | 1.10 (0.92 to 1.32) |
| ≥30 | 206 (18.0) | 371 (16.5) | 1.21 (0.99 to 1.48) | 1.09 (0.88 to 1.34) |
| Missing | 128 (11.2) | 219 (9.7) | 1.28 (1.00 to 1.63) | 1.24 (0.95 to 1.61) |
| Coexisting medical conditions† | ||||
| No | 1045 (91.4) | 2126 (94.2) | 1.0 | 1.0 |
| Yes | 93 (8.1) | 103 (4.6) | 1.84 (1.38 to 2.46) | 1.60 (1.18 to 2.17) |
| Missing | 6 (0.5) | 27 (1.2) | 0.45 (1.18 to 1.10) | 0.76 (0.17 to 3.41) |
| Parity | ||||
| Nulliparous | 403 (35.2) | 984 (43.6) | 1.0 | No significant effect on fit of model (excluded) |
| Multiparous | 738 (64.5) | 1250 (55.4) | 1.44 (1.24 to 1.67) | |
| Missing | 3 (0.3) | 22 (1.0) | 0.33 (0.10 to 1.12) | |
| Multiple pregnancy | ||||
| No | 1083 (94.7) | 2211 (98.0) | 1.0 | 1.0 |
| Yes | 59 (5.2) | 27 (1.2) | 4.46 (2.81 to 7.08) | 3.88 (2.42 to 6.22) |
| Missing | 2 (0.2) | 18 (0.8) | 0.23 (0.53 to 0.98) | 0.20 (0.02 to 2.54) |
| Past pregnancy conditions‡ | ||||
| No | 1041 (91.0) | 2121 (94.0) | 1.0 | 1.0 |
| Yes | 94 (8.2) | 104 (4.6) | 1.81 (1.38 to 2.46) | 1.58 (1.16 to 2.14) |
| Missing | 9 (0.8) | 31 (1.4) | 0.59 (0.28 to 1.25) | 1.12 (0.36 to 3.54) |
*All variables adjusted for all other variables in the table.
†Cardiac disease, diabetes mellitus, epilepsy, essential hypertension, haematological disorders, past thrombotic event, recent/current anticoagulation, intravenous drug use and/or alcohol abuse.
‡Amniotic fluid embolism, gestational diabetes, pregnancy-induced hypertension, pre-eclampsia, eclampsia, thrombotic event, acute fatty liver of pregnancy, manual removal of placenta, placenta accreta, past classical caesarean section.
BMI, body mass index.