Table 2. Summary risk estimates of the association between parity number and cardiovascular disease mortality (per 1 live birth).
| No. of | Summary RR | I2 Value | Ph* | |
|---|---|---|---|---|
| studies | (95% CIs) | (%) | ||
| Overall | 9 | 1.01 (0.97–1.05) | 86.4 | <0.001 |
| Subgroup analyses | ||||
| Number of cases | ||||
| ≤500 | 4 | 1.07 (0.98–1.16) | 82.8 | 0.001 |
| >500 | 5 | 0.97 (0.94–1.01) | 78.3 | 0.001 |
| Geographic Location | ||||
| North America | 5 | 0.97 (0.94–1.01) | 77.3 | 0.001 |
| Europe | 1 | 1.05 (0.98–1.12) | N/A | N/A |
| Asia | 3 | 1.07 (0.97–1.19) | 88.5 | <0.001 |
| Adjustment for potential confounders | ||||
| Age | ||||
| Yes | 7 | 1.03 (0.98–1.07) | 82.2 | <0.001 |
| No | 2 | 0.97 (0.90–1.04) | 79.9 | 0.026 |
| BMI | ||||
| Yes | 4 | 1.00 (0.97–1.03) | 58.5 | 0.065 |
| No | 5 | 1.02 (0.93–1.12) | 91.3 | <0.001 |
| DM | ||||
| Yes | 1 | 1.20 (1.12–1.29) | N/A | N/A |
| No | 8 | 0.99 (0.96–1.02) | 75.2 | <0.001 |
| Hypertension | ||||
| Yes | 3 | 1.06 (0.98–1.14) | 93.0 | <0.001 |
| No | 6 | 0.98 (0.94–1.03) | 65.2 | 0.013 |
| Alcohol drinking | ||||
| Yes | 1 | 1.02 (0.99–1.06) | N/A | N/A |
| No | 8 | 1.01 (0.97–1.05) | 87.2 | <0.001 |
| Cigarette smoking | ||||
| Yes | 4 | 1.05 (0.99–1.12) | 90.0 | <0.001 |
| No | 5 | 0.95 (0.93–0.97) | 46.7 | 0.112 |
BMI: body mass index; CI: confidence interval; DM: diabetes mellitus; N/A: not available; RR: relative risk.
*P value for heterogeneity within each subgroup.