RR of CHD in twins versus singletons, according to CHD severity and chorionicity
| CHD severity | Twins (any chorionicity) RR (95% CI); p value | Dichorionic twins RR (95% CI); p value | Monochorionic twins RR (95% CI); p value | |||
|---|---|---|---|---|---|---|
| Unadjusted | Adjusted* | Unadjusted | Adjusted* | Unadjusted | Adjusted* | |
| All CHD | 1.73 (1.48 to 2.04); p<0.001 | 1.75 (1.48 to 2.06); p<0.001 | 1.49 (1.22 to 1.83); p<0.001 | 1.51 (1.24 to 1.86); p<0.001 | 2.72 (2.04 to 3.62); p<0.001 | 2.76 (2.07 to 3.69); p<0.001 |
| Severe CHD | 1.78 (0.83 to 3.82); p=0.14 | 1.82 (0.85 to 3.90); p=0.12 | 1.41 (0.52 to 3.80); p=0.50 | 1.39 (0.51 to 3.76); p=0.52 | 3.92 (1.25 to 12.30); p=0.02 | 3.90 (1.24 to 12.27); p=0.02 |
| Moderate CHD | 1.46 (1.02 to 2.10); p=0.04 | 1.54 (1.07 to 2.20); p=0.02 | 1.63 (1.09 to 2.43); p=0.02 | 1.67 (1.12 to 2.49); p=0.01 | 1.21 (0.50 to 2.92); p=0.67 | 1.24 (0.51 to 2.98); p=0.64 |
| Mild CHD | 1.81 (1.49 to 2.20); p<0.001 | 1.80 (1.47 to 2.20); p<0.001 | 1.49 (1.16 to 1.91); p=0.002 | 1.50 (1.17 to 1.13); p=0.001 | 3.07 (2.20 to 4.28); p<0.001 | 3.12 (2.23 to 4.36); p<0.001 |
*Adjusted for year of delivery and maternal age. Maternal age was missing in 29 (0.7%) singleton cases and so these cases were excluded. Maternal age data were missing in 2.1% of twins without CHD so these were excluded from the denominator.
CHD, congenital heart disease; RR, relative risk.