Table 2.
Published and calculated relative risks and odds ratios for cohort studies
| No of studies | No of women | Unadjusted relative risk (95% CI) | I2 | Published risk (odds ratio or relative risk), 95% CI (adjustment) | |
|---|---|---|---|---|---|
| Antiphospholipid antibodies v none | 238,39 | 1802 | 9.72 (4.34 to 21.75) | 55.9% | NA |
| Pre-existing diabetes v none | 312,31,35 | 56 968 | 3.56 (2.54 to 4.99) | 0% | 5.58, 2.72 to 11.4331 (smoking status, No of fetuses, season of birth, place of birth) |
| Previous pre-eclampsia v none | 512,20-23 | 24 620 | 7.19 (5.85 to 8.83) | 0% | NA |
| Family history v no family history | 227,28 | 692 | 2.90 (1.70 to 4.93) | 0% | NA |
| Nulliparity v multiparity | 310-12 | 37 988 | 2.91 (1.28 to 6.61) | 94.3% | 3.10, 1.55 to 6.1713 (age, result of glucose challenge test); 3.0, 2.1 to 4.214 (age, BMI, smoking status, education, employment) |
| Twin v singleton pregnancy | 510,12,18,30,31 | 53 028 | 2.93 (2.04 to 4.21) | 72.7% | 4.17, 2.30 to 7.5531 (smoking status, diabetes, season of birth, place of birth) |
| Triplet v twin pregnancy | 134 | 76 | 2.83 (1.25 to 6.40) | — | NA |
| Raised v normal BMI at booking | 349-51 | 4625 | 1.55 (1.28 to 1.88) | 0% | 1.9, 0.7 to 4.855 (all parity, BMI ≥25); 9.3, 2.0 to 48.055 (primiparas only, BMI ≥25) |
| Raised v normal BMI before pregnancy | 612,16,31,46-48 | 64 789 | 2.47 (1.66 to 3.67) | 85.9% | 1.8, 1.0 to 3.214 (age, parity, smoking status, education, employment); 3.14, 1.44 to 6.8331 (BMI 26.1-29.0 v normal BMI adjusted for smoking, place and season of birth, diabetes); 5.19, 2.35 to 11.4831 (BMI >29.0 v normal BMI adjusted for smoking, place, season of birth, diabetes); RR 2.1, 1.0 to 4.648 (BMI ≥30 before pregnancy adjusted for age, parity, diabetes, maternal and paternal hypertension, smoking status, history of raised cholesterol) |
| Systolic ≥130 mm Hg v <130 mm Hg at booking | 118 | 906 | 2.37 (1.78 to 3.15) | — | 3.6, 2.0 to 6.618 (previous pre-eclampsia, parity, maternal weight, smoking status, No of fetuses) |
| Diastolic ≥80 mm Hg v <80 mm Hg at booking | 118 | 907 | 1.38 (1.01 to 1.87) | — | 1.8, 0.7 to 4.618 (previous pre-eclampsia, parity, maternal weight, smoking status, No of fetuses) |
| Maternal age (years): | |||||
| ≤17 v>17 | 156 | 161 | 2.98 (0.39 to 22.76) | — | NA |
| ≤16 v>16 | 410,53,57,58 | 11 589 | 1.24 (0.69 to 2.23) | 78.3% | NA |
| ≤19 v>19 | 311,12,31 | 15 295 | 1.02 (0.59 to 1.74) | 23.0% | NA |
| ≥35 v<35 | 311,12,17 | 65 314 | 0.64 (0.03 to 13.33) | 99.8% | 2.5, 1.5 to 4.114 (parity, BMI, smoking status, education, employment); 1.09, 1.02 to 1.1713 (gravidity and glucose challenge test result) |
| Age ≥40 v <40 multiparas | 18 | 3140 | 1.96 (1.34 to 2.87) | — | NA |
| Age ≥40 v <40 primiparas | 18 | 5242 | 1.68 (1.23 to 2.29) | — | NA |
| For each year increase in age | — | — | — | — | RR 1.3, 1.0 to 1.59 |
| >59 v 18-23 months between births | — | — | — | — | RR 1.83, 1.72 to 1.9444 |
| For each year increase in interval | — | — | — | — | 1.12, 1.11 to 1.1343 (change of partner, maternal age, year of delivery) |
BMI=body mass index; NA=not available; RR=relative risk.