Table 3. Cosibling Analyses of Gestational Age at Birth and Risk of Heart Failure, Sweden, 1973 Through 2015.
| Characteristica | Cases | Hazard ratio (95% CI)b | P value |
|---|---|---|---|
| Attained ages 0-43 y | |||
| Preterm | 362 | 2.92 (2.37-3.60) | <.001 |
| Early term | 674 | 1.36 (1.18-1.55) | <.001 |
| Full term | 1934 | 1 [Reference] | NA |
| Per additional week | NA | 0.86 (0.83-0.88) | <.001 |
| Attained ages <1 y | |||
| Preterm | 190 | 4.41 (3.24-5.99) | <.001 |
| Early term | 294 | 1.76 (1.42-2.18) | <.001 |
| Full term | 623 | 1 [Reference] | NA |
| Per additional week | NA | 0.81 (0.78-0.85) | <.001 |
| Attained ages 1-17 y | |||
| Preterm | 82 | 3.50 (2.25-5.46) | <.001 |
| Early term | 145 | 1.56 (1.17-2.09) | <.001 |
| Full term | 360 | 1 [Reference] | NA |
| Per additional week | NA | 0.80 (0.75-0.86) | <.001 |
| Attained ages 18-43 y | |||
| Preterm | 90 | 1.14 (0.75-1.73) | .54 |
| Early term | 235 | 0.90 (0.71-1.13) | .37 |
| Full term | 951 | 1 [Reference] | NA |
| Per additional week | NA | 0.99 (0.94-1.05) | .80 |
Abbreviation: NA, not applicable.
a
Preterm birth was defined as any at gestational age less than 37 weeks; early term, at 37 to 38 weeks’ gestational age; and full term, 39 to 41 weeks’ gestational age.
b
Adjusted for shared familial (genetic and/or environmental) factors and additionally for specific child characteristics (birth year, sex, birth order, and family history of heart failure or ischemic heart disease) and maternal characteristics (age, education, birth country, body mass index, smoking, preeclampsia, other hypertensive disorders, and diabetes).