Table 3.
Associations between women’s pregnancy duration and subsequent risk of hemorrhagic or ischemic stroke.
| Hemorrhagic stroke | Ischemic stroke | |||||
|---|---|---|---|---|---|---|
| Cases | HR (95% CI)* | P | Cases | HR (95% CI)* | P | |
| 0-43 years after delivery | ||||||
| Preterm (<37 wks) | 1,728 | 1.31 (1.25, 1.38) | <0.001 | 2,415 | 1.54 (1.47, 1.61) | <0.001 |
| Extremely preterm (22-27 wks) | 71 | 1.40 (1.11, 1.77) | 0.005 | 122 | 2.11 (1.77, 2.53) | <0.001 |
| Very preterm (28-33 wks) | 469 | 1.48 (1.35, 1.63) | <0.001 | 658 | 1.76 (1.62, 1.90) | <0.001 |
| Late preterm (34-36 wks) | 1,188 | 1.25 (1.18, 1.33) | <0.001 | 1,635 | 1.44 (1.37, 1.52) | <0.001 |
| Early term (37-38 wks) | 3,950 | 1.13 (1.09, 1.18) | <0.001 | 4,802 | 1.17 (1.13, 1.21) | <0.001 |
| Full-term (39-41 wks) | 9,253 | Reference | 11,466 | Reference | ||
| Post-term (≥42 wks) | 877 | 1.06 (0.99, 1.14) | 0.09 | 1,149 | 1.01 (0.95, 1.07) | 0.82 |
| Per additional week (trend) | 0.96 (0.96, 0.97) | <0.001 | 0.94 (0.94, 0.95) | <0.001 | ||
| <10 years after delivery | ||||||
| Preterm (<37 wks) | 263 | 1.50 (1.31, 1.72) | <0.001 | 195 | 1.98 (1.68, 2.33) | <0.001 |
| Extremely preterm (22-27 wks) | 15 | 1.78 (1.05, 3.01) | 0.03 | 21 | 4.62 (2.98, 7.15) | <0.001 |
| Very preterm (28-33 wks) | 84 | 1.95 (1.56, 2.44) | <0.001 | 60 | 2.36 (1.79, 3.11) | <0.001 |
| Late preterm (34-36 wks) | 164 | 1.32 (1.12, 1.56) | 0.001 | 114 | 1.67 (1.36, 2.04) | <0.001 |
| Early term (37-38 wks) | 550 | 1.16 (1.05, 1.28) | 0.005 | 297 | 1.15 (1.00, 1.32) | 0.05 |
| Full-term (39-41 wks) | 1,313 | Reference | 692 | Reference | ||
| Post-term (≥42 wks) | 122 | 1.03 (0.85, 1.24) | 0.77 | 54 | 0.89 (0.67, 1.18) | 0.42 |
| Per additional week (trend) | 0.95 (0.93, 0.97) | <0.001 | 0.91 (0.89, 0.92) | <0.001 | ||
| 10-19 years after delivery | ||||||
| Preterm (<37 wks) | 462 | 1.45 (1.31, 1.60) | <0.001 | 444 | 1.93 (1.73, 2.15) | <0.001 |
| Extremely preterm (22-27 wks) | 18 | 1.37 (0.86, 2.19) | 0.18 | 36 | 3.68 (2.63, 5.15) | <0.001 |
| Very preterm (28-33 wks) | 128 | 1.62 (1.35, 1.94) | <0.001 | 127 | 2.22 (1.84, 2.67) | <0.001 |
| Late preterm (34-36 wks) | 316 | 1.39 (1.23, 1.57) | <0.001 | 281 | 1.73 (1.52, 1.97) | <0.001 |
| Early term (37-38 wks) | 1,006 | 1.20 (1.11, 1.30) | <0.001 | 745 | 1.29 (1.18, 1.41) | <0.001 |
| Full-term (39-41 wks) | 2,044 | Reference | 1,400 | Reference | ||
| Post-term (≥42 wks) | 158 | 1.00 (0.85, 1.18) | 0.98 | 103 | 0.88 (0.72, 1.08) | 0.23 |
| Per additional week (trend) | 0.95 (0.94, 0.96) | <0.001 | 0.91 (0.90, 0.92) | <0.001 | ||
| 20-29 years after delivery | ||||||
| Preterm (<37 wks) | 554 | 1.22 (1.11, 1.33) | <0.001 | 772 | 1.44 (1.33, 1.56) | <0.001 |
| Extremely preterm (22-27 wks) | 18 | 1.07 (0.67, 1.71) | 0.77 | 33 | 1.70 (1.21, 2.40) | 0.002 |
| Very preterm (28-33 wks) | 134 | 1.23 (1.04, 1.47) | 0.02 | 214 | 1.67 (1.46, 1.92) | <0.001 |
| Late preterm (34-36 wks) | 402 | 1.22 (1.10, 1.35) | <0.001 | 525 | 1.35 (1.23, 1.48) | <0.001 |
| Early term (37-38 wks) | 1,386 | 1.16 (1.09, 1.24) | <0.001 | 1,671 | 1.21 (1.15, 1.29) | <0.001 |
| Full-term (39-41 wks) | 2,985 | Reference | 3,526 | Reference | ||
| Post-term (≥42 wks) | 278 | 1.11 (0.98, 1.25) | 0.11 | 345 | 1.07 (0.96, 1.20) | 0.21 |
| Per additional week (trend) | 0.97 (0.96, 0.98) | <0.001 | 0.95 (0.94, 0.96) | <0.001 | ||
| 30-43 years after delivery | ||||||
| Preterm (<37 wks) | 449 | 1.23 (1.11, 1.36) | <0.001 | 1,004 | 1.41 (1.32, 1.51) | <0.001 |
| Extremely preterm (22-27 wks) | 20 | 1.63 (1.05, 2.53) | 0.03 | 32 | 1.33 (0.94, 1.89) | 0.11 |
| Very preterm (28-33 wks) | 123 | 1.44 (1.20, 1.73) | <0.001 | 257 | 1.55 (1.37, 1.76) | <0.001 |
| Late preterm (34-36 wks) | 306 | 1.15 (1.02, 1.29) | 0.02 | 715 | 1.37 (1.27, 1.48) | <0.001 |
| Early term (37-38 wks) | 1,008 | 1.04 (0.97, 1.12) | 0.30 | 2,089 | 1.10 (1.05, 1.16) | <0.001 |
| Full-term (39-41 wks) | 2,911 | Reference | 5,848 | Reference | ||
| Post-term (≥42 wks) | 319 | 1.06 (0.95, 1.20) | 0.30 | 647 | 1.01 (0.93, 1.10) | 0.82 |
| Per additional week (trend) | 0.97 (0.96, 0.98) | <0.001 | 0.96 (0.95, 0.97) | <0.001 | ||
*
Adjusted for maternal age (as Cox model time scale), year of delivery, parity, education, employment, income, region of origin, BMI, smoking, preeclampsia, other hypertensive disorders, and diabetes prior to delivery.