Table 2. Incidence Rates and Hazard Ratios With 95% CIs for Ischemic Heart Disease According to Maternal Preeclampsia and Its Subtypes.
| Exposure | Population analysis (n = 8 475 819) | Sibling analysis (n = 7 031 134) | ||||||
|---|---|---|---|---|---|---|---|---|
| No. of events | Rate per 10 000 person-years | HR (95% CI) | No. of events | Rate per 10 000 person-years | HR (95% CI) | |||
| Crude | Adjusteda | Crude | Adjusteda | |||||
| Normotensive pregnancy | 7237 | 0.46 | 1 [Reference] | 1 [Reference] | 5 225 | 0.40 | 1 [Reference] | 1 [Reference] |
| Preeclampsia | 133 | 0.42 | 1.50 (1.26-1.78) | 1.33 (1.12-1.58) | 93 | 0.36 | 0.81 (0.58-1.12) | 0.82 (0.59-1.15) |
| Onset of preeclampsiab | ||||||||
| Late onset | 92 | 0.37 | 1.58 (1.28-1.94) | 1.31 (1.06-1.61) | 55 | 0.27 | 0.70 (0.45-1.10) | 0.64 (0.37-1.11) |
| Early onset | 19 | 0.41 | 2.08 (1.32-3.26) | 1.62 (1.03-2.55) | 13 | 0.38 | 1.60 (0.59-4.39) | 2.58 (0.79-8.43) |
| Severity of preeclampsiab | ||||||||
| Mild or moderate | 110 | 0.45 | 1.50 (1.24-1.81) | 1.33 (1.10-1.61) | 79 | 0.39 | 0.78 (0.55-1.11) | 0.79 (0.55-1.13) |
| Severe | 23 | 0.33 | 1.53 (1.01-2.30) | 1.33 (0.89-2.01) | 14 | 0.26 | 0.95 (0.42-2.13) | 1.07 (0.47-2.45) |
| Preeclampsia with or without SGAb | ||||||||
| Without SGA | 83 | 0.37 | 1.61 (1.30-2.01) | 1.32 (1.06-1.64) | 50 | 0.28 | 0.74 (0.47-1.17) | 0.64 (0.36-1.13) |
| With SGA | 28 | 0.39 | 1.78 (1.23-2.59) | 1.50 (1.03-2.18) | 18 | 0.33 | 1.04 (0.45-2.41) | 1.55 (0.57-4.18) |
| Other hypertensive disorders during pregnancy | ||||||||
| Preexisting chronic hypertension | 14 | 0.33 | 2.19 (1.30-3.70) | 1.72 (1.02-2.92) | 11 | 0.30 | 0.94 (0.34-2.63) | 0.87 (0.30-2.50) |
| Gestational hypertension | 64 | 0.41 | 1.56 (1.22-1.99) | 1.44 (1.12-1.84) | 54 | 0.42 | 0.89 (0.57-1.37) | 0.91 (0.58-1.41) |
Abbreviations: HR, hazard ratio; SGA, small for gestational age (birth weight below the 10th percentile of the sex-specific and gestational age–specific standard curve for normal fetal growth).
Analyses were adjusted for offspring calendar year of birth; offspring sex; and maternal parity, age, educational level, marital status, and diabetes status before childbirth.
The variables onset of preeclampsia (early vs late), severity of preeclampsia (mild or moderate vs severe), and preeclampsia with or without SGA were categorical variables, each with 3 subgroups including normotensive pregnancy as the reference for all 3 variables (1 for unexposed and 2 for exposed). The difference in the strength of the associations between less severe and severe forms of preeclampsia with ischemic heart disease risk was formally tested. The P values were P = .27 for the difference between late-onset and early-onset preeclampsia, P = .93 for the difference between mild or moderate and severe preeclampsia, and P = .64 for the difference between preeclampsia without SGA and with SGA.