Background
Materials and methods
Sibling data and exclusion criteria
Outcome variable
Pregnancy complications
Analyses
Results
Characteristic | Number of total births | CVD deaths a | ||
---|---|---|---|---|
1 birth: N (%) | 2 births: N (%) | 3 + births: N (%) | N (%) | |
Mothers’ birth year b | ||||
1922–1948 | 25 969 (20.0) | 63 786 (17.5) | 40 246 (14.9) | 1935 (38.6) |
1949–1974 | 104 023 (80.0) | 301 349 (82.5) | 229 753 (85.1) | 3080 (61.4) |
Total | 129 992 (100.0) | 365 135 (100.0) | 269 999 (100.0) | 5015 (100.0) |
Mother’s age at first birth (years) | ||||
< 20 | 10 838 (6.4) | 33 765 (6.9) | 45 919 (13.2) | 753 (14.9) |
20–24 | 44 210 (25.9) | 168 674 (34.3) | 158 536 (45.4) | 2354 (46.5) |
25–29 | 50 747 (29.8) | 184 046 (37.4) | 111 995 (32.1) | 1,267 (25.0) |
30–34 | 37 719 (22.1) | 86 111 (17.5) | 29 682 (8.5) | 481 (9.5) |
35–39 | 20 569 (12.1) | 18 186 (3.7) | 3060 (0.9) | 157 (3.1) |
40+ | 6359 (3.7) | 1262 (0.2) | 91 (0.03) | 50 (1.0) |
Total | 170 442 (100.0) | 492 041 (100.0) | 349 283 (100.0) | 5062 (100.0) |
Mother’s education c | ||||
Low (< 11 years) | 38 077 (23.0) | 83 973 (17.2) | 71 550 (20.6) | 2052 (40.8) |
Middle (11–14 years) | 65 165 (39.4) | 194 720 (39.8) | 129 546 (37.3) | 2265 (45.0) |
High (> 14 years) | 62 011 (37.5) | 210 484 (43.0) | 146 313 (42.1) | 714 (14.2) |
Total | 165 253 (100.0) | 489 177 (100.0) | 347 409 (100.0) | 5031 (100.0) |
Reproduction | Total N | CVD deaths a: N (row %) | Crude HR (95% CI) | Adjusted HR (95%CI) b | Adjusted HR (95%CI) c |
---|---|---|---|---|---|
One child only
| |||||
No complications | 128 586 (14.0) | 815 (0.63) | 1.54 (1.42–1.69) | 1.47 (1.34–1.61) | 1.47 (1.34–1.61) |
Complication | 41 854 (4.6) | 510 (1.22) | 2.82 (2.54–3.12) | 2.50 (2.25–2.78) | 2.48 (2.23–2.76) |
Two births
| |||||
No complications | 359 911 (39.2) | 1275 (0.35) | Reference | Reference | Reference |
Complication only first | 69 470 (7.6) | 384 (0.55) | 1.48 (1.32–1.66) | 1.41 (1.26–1.58) | 1.40 (1.24–1.57) |
Complication only last | 35 221 (3.8) | 267 (0.76) | 1.94 (1.70–2.21) | 1.82 (1.59–2.08) | 1.76 (1.53–2.01) |
Three births
| |||||
No complications | 178 612 (19.5) | 518 (0.29) | 1.03 (0.93–1.34) | 1.04 (0.94–1.15) | 1.04 (0.93–1.15) |
Complication only first | 32 744 (3.6) | 157 (0.48) | 1.54 (1.31–1.82) | 1.49 (1.27–1.76) | 1.49 (1.25–1.77) |
Complication only last | 14 795 (1.6) | 103 (0.70) | 2.24 (1.83–2.74) | 2.06 (1.68–2.52) | 2.05 (1.66–2.53) |
Four births
| |||||
No complications | 35 035 (3.8) | 114 (0.33) | 1.29 (1.07–1.57) | 1.25 (1.03–1.52) | 1.26 (1.04–1.54) |
Complication only first | 6827 (0.7) | 34 (0.50) | 1.85 (1.31–2.60) | 1.74 (1.24–2.45) | 1.74 (1.18–2.57) |
Complication only last | 3149 (0.3) | 26 (0.83) | 3.19 (2.16–4.70) | 2.85 (1.93–4.20) | 3.18 (2.16–4.70) |
Five-eight births
| |||||
No complications | 8000 (0.9) | 38 (0.47) | 2.28 (1.65–3.15) | 2.15 (1.56–2.97) | 2.17 (1.56–3.03) |
Complication only first | 1595 (0.2) | 12 (0.75) | 3.27 (1.85–5.77) | 2.88 (1.63–5.08) | 3.31 (1.83–5.99) |
Complication only last | 1795 (0.2) | 20 (1.11) | 5.19 (3.34–8.08) | 4.49 (2.88–6.99) | 4.55 (2.68–7.71) |
Total number of mothers d | 917 594 | 4273 | 917 594 | 908 405 | 896 463 |
Reproduction | Total N | CVD deaths a : N (row %) | Crude HR (95% CI) | Adjusted HR (95%CI) b |
---|---|---|---|---|
Mothers’ birth year 1922–1948: N = 118 107
| ||||
One child only
| ||||
No complication | 18 833 (16.0) | 334 (1.77) | 1.67 (1.45–1.92) | 1.61 (1.40–1.85) |
Complication | 7136 (6.0) | 209 (2.93) | 2.84 (2.42–3.35) | 2.54 (2.15–2.99) |
Two births
| ||||
No complications | 45 062 (38.2) | 487 (1.08) | Reference | Reference |
Complication only first | 9599 (8.1) | 147 (1.53) | 1.43 (1.19–1.71) | 1.37 (1.14–1.65) |
Complication only last | 4,989 (4.2) | 97 (1.94) | 1.85 (1.49–2.30) | 1.74 (1.40–2.17) |
Three-eight births
| ||||
No complications | 24 214 (20.5) | 227 (0.94) | 0.94 (0.80–1.10) | 0.93 (0.80–1.09) |
Complication only first | 5075 (4.3) | 76 (1.50) | 1.50 (1.18–1.91) | 1.44 (1.13–1.83) |
Complication only last | 3199 (2.7) | 63 (1.97) | 2.08 (1.60–2.70) | 1.85 (1.43–2.41) |
Mothers’ birth year 1949–1974: N = 577 472
| ||||
One child only
| ||||
No complication | 78 035 (13.5) | 474 (0.61) | 1.45 (1.29–1.62) | 1.45 (1.29–1.63) |
Complication | 25 986 (4.5) | 296 (1.14) | 2.69 (2.35–3.08) | 2.57 (2.25–2.94) |
Two births
| ||||
No complications | 218 727 (37.9) | 778 (0.36) | Reference | Reference |
Complication only first | 42 506 (7.4) | 234 (0.55) | 1.49 (1.29–1.72) | 1.42 (1.23–1.65) |
Complication only last | 22 697 (3.9) | 167 (0.74) | 1.95 (1.65–2.30) | 1.83 (1.55–2.17) |
Three-eight births
| ||||
No complications | 144 384 (25.0) | 437 (0.30) | 1.20 (1.06–1.35) | 1.18 (1.05–1.33) |
Complication only first | 26 995 (4.7) | 127 (0.47) | 1.73 (1.43–2.08) | 1.64 (1.35–1.97) |
Complication only last | 18 142 (3.1) | 140 (0.77) | 2.92 (2.44–3.49) | 2.62 (2.18–3.14) |