Table 2. Hazard ratios (95% confidence intervals) for incident coronary heart disease associated with parity in all women and history of breastfeeding in parous women only.
| Model I | Model II | Model III | |
|---|---|---|---|
| Parity, n | 12,319 | 12,319 | 12,319 |
| Parous vs. not | 1.27 (1.09, 1.47) | 1.24 (1.07, 1.44) | 1.19 (1.01, 1.41) |
| I2 for heterogeneity (95% CI) | 7% (0%, 67%) | 0% (0%, 65%) | 0% (0%, 65%) |
| Number of children, n | 9,701 | 9,701 | 9,701 |
| None | 1.00 (0.82, 1.22) | 1.00 (0.82, 1.22) | 1.00 (0.82, 1.23) |
| 1 child | 1.21 (1.00, 1.45) | 1.16 (0.95, 1.42) | 1.17 (0.92, 1.49) |
| 2 children | 1.21 (1.10, 1.33) | 1.17 (1.10, 1.25) | 1.15 (1.02, 1.28) |
| 3 children | 1.21 (1.05, 1.39) | 1.20 (1.02, 1.40) | 1.15 (0.94, 1.40) |
| 4 children | 1.46 (1.20, 1.77) | 1.43 (1.18, 1.75) | 1.39 (1.14, 1.70) |
| 5 or more children | 2.19 (1.41, 3.38) | 2.02 (1.27, 3.20) | 1.95 (1.19, 3.20) |
| Breastfeeding, n | 8,044 | 8,044 | 8,044 |
| Ever vs. never | 0.71 (0.59, 0.85) | 0.69 (0.57, 0.85) | 0.71 (0.52, 0.98) |
| I2 for heterogeneity | 8% (0%, 73%) | 16% (0%, 59%) | 58% (2%, 82%) |
| Lifetime duration of breastfeeding, n | 8,012 | 8,012 | 8,012 |
| Never breastfed | 1.00 (0.84, 1.19) | 1.00 (0.83, 1.21) | 1.00 (0.75, 1.34) |
| >0 to >3 months | 0.69 (0.57, 0.83) | 0.69 (0.57, 0.83) | 0.73 (0.60, 0.89) |
| ≥3 to <6 months | 0.71 (0.55, 0.91) | 0.73 (0.60, 0.88) | 0.68 (0.56, 0.83) |
| ≥6 to <12 months | 0.73 (0.61, 0.87) | 0.70 (0.58, 0.84) | 0.69 (0.55, 0.87) |
| ≥12 to <23 months | 0.65 (0.57, 0.74) | 0.63 (0.53, 0.74) | 0.63 (0.51, 0.76) |
| ≥23 months | 0.66 (0.50, 0.87) | 0.60 (0.46, 0.78) | 0.62 (0.45, 0.86) |
| Duration of breastfeeding per child, n | 8,012 | 8,012 | 8,012 |
| Never breastfed | 1.00 (0.85, 1.17) | 1.00 (0.84, 1.20) | 1.00 (0.73, 1.37) |
| >0 to <1 months | 0.79 (0.66, 0.94) | 0.73 (0.61, 0.88) | 0.77 (0.63, 0.94) |
| ≥1 to <3 months | 0.72 (0.62, 0.85) | 0.71 (0.61, 0.83) | 0.69 (0.61, 0.78) |
| ≥3 to <6 months | 0.66 (0.56, 0.78) | 0.65 (0.55, 0.75) | 0.67 (0.57, 0.77) |
| ≥6 months | 0.63 (0.51, 0.78) | 0.66 (0.53, 0.82) | 0.67 (0.56, 0.80) |
Analyses of parity are conducted in all women. Analyses of breastfeeding are conducted in parous women only.
Model I: Adjusted for age at study entry and centre; Model II: model I + level of attained education, smoking status, and number of livebirths (for breastfeeding history only); Model III: model II + high blood pressure, HDL cholesterol, total cholesterol, history of diabetes mellitus, and BMI.