Risk of the secondary outcomes in relation to plurality and the hypertensive disorders of pregnancy using people with a singleton birth with no hypertensive disorders as the reference group
| Outcome | Singleton birth, no HDP (referent) n = 1 431 651 | Singleton birth, with HDP n = 98 631 | Twin birth, no HDP n = 21 046 | Twin birth, with HDP n = 4283 | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| No. events | Incidence rate (per 1000 person-year, 95% CI) | No. events | Incidence rate (per 1000 person-year, 95% CI) | Unadjusted HR (95% CI) | Adjusted HR* (95% CI) | No. events | Incidence rate (per 1000 person-year, 95% CI) | Unadjusted HR (95% CI) | Adjusted HR* (95% CI) | No. events | Incidence rate (per 1000 person-year, 95% CI) | Unadjusted HR (95% CI) | Adjusted HR* (95% CI) | |
| Heart failure | 1466 | 0.08 (0.08–0.08) | 266 | 0.21 (0.19–0.24) | 2.70 (2.37–3.08) | 2.20 (1.92–2.51) | 28 | 0.11 (0.08–0.16) | 1.46 (1.00–2.11) | 1.37 (0.92–2.01) | 8 | 0.15 (0.08–0.31) | 2.02 (1.01–4.05) | 1.74 (0.87–3.48) |
| Cardiac dysrhythmia | 1976 | 0.11 (0.10–0.11) | 236 | 0.19 (0.17–0.22) | 1.78 (1.55–2.03) | 1.55 (1.34–1.77) | 28 | 0.15 (0.11–0.20) | 1.43 (1.03–1.97) | 1.33 (0.96–1.85) | 9 | 0.17 (0.09–0.34) | 1.68 (0.87–3.24) | 1.44 (0.75–2.77) |
| Coronary artery disease | 8139 | 0.45 (0.44–0.46) | 1208 | 0.98 (0.92–1.03) | 2.23 (2.10–2.37) | 1.91 (1.80–2.03) | 125 | 0.50 (0.42–0.59) | 1.19 (0.99–1.41) | 1.11 (0.93–1.33) | 35 | 0.68 (0.49–0.95) | 1.61 (1.16–2.25) | 1.37 (0.98–1.91) |
| Cerebrovascular disease | 1764 | 0.10 (0.09–0.10) | 290 | 0.23 (0.21–0.26) | 2.45 (2.16–2.77) | 2.13 (1.88–2.42) | 19 | 0.08 (0.05–0.12) | 0.82 (0.52–1.28) | 0.80 (0.51–1.26) | 8 | 0.16 (0.08–0.31) | 1.67 (0.83–3.35) | 1.51 (0.76–3.04) |
| Peripheral artery disease | 1608 | 0.09 (0.08–0.09) | 149 | 0.12 (0.10–0.14) | 1.37 (1.16–1.62) | 1.24 (1.04–1.46) | 14 | 0.06 (0.03–0.09) | 0.64 (0.38–1.09) | 0.63 (0.37–1.06) | ≤ 5† | 0.04 (0.01–0.15) | 0.45 (0.11–1.80) | 0.41 (0.10–1.64) |
| All-cause mortality | 10 183 | 0.56 (0.55–0.57) | 922 | 0.74 (0.69–0.79) | 1.35 (1.26–1.44) | 1.23 (1.14–1.31) | 152 | 0.60 (0.51–0.71) | 1.13 (0.96–1.33) | 1.09 (0.92–1.28) | 28 | 0.54 (0.37–0.79) | 1.01 (0.70–1.47) | 0.93 (0.64–1.35) |
Note: CI = confidence interval, HDP = hypertensive disorders of pregnancy (pre-eclampsia or gestational hypertension), HR = hazard ratio.
↵* Adjusted for age at first birth, neighbourhood income quintile, world region of origin, assisted reproductive technology, and cardiovascular risk factors present at baseline before the first pregnancy.
↵† Data suppressed because of small cell size.