Table 4.
Hazard ratios (95% confidence intervals) for history of preterm deliveries and cardiovascular events (MI and stroke) at age 40 or later, among women with no births at age 40 or later
| First Pregnancy | 2nd+ pregnancies | N (%)* | Cases/Person-Years* | Model 1 | Model 2 | Model 3 | Model 4 |
|---|---|---|---|---|---|---|---|
| Term | Term | 48,015 (71.2) | 558/893,230 | 1.00 (ref) | 1.00 (ref) | 1.00 (ref) | 1.00 (ref) |
| Term | Preterm | 3,597 (5.3) | 56/66,083 | 1.34 (1.02, 1.77) | 1.31 (1.00, 1.73) | 1.30 (0.99, 1.71) | 1.34 (1.01, 1.76) |
| Term | None | 9,938 (14.7) | 151/190,761 | 1.35 (1.12, 1.62) | 1.26 (1.05, 1.52) | 1.23 (1.02, 1.48) | 1.21 (0.99, 1.46) |
| Preterm | Term | 2,615 (3.9) | 40/46,887 | 1.43 (1.04, 1.97) | 1.41 (1.02, 1.94) | 1.37 (0.99, 1.89) | 1.38 (1.00, 1.90) |
| Preterm | Preterm | 1,863 (2.8) | 40/35,342 | 1.72 (1.25, 2.38) | 1.67 (1.21, 2.30) | 1.63 (1.18, 2.25) | 1.65 (1.20, 2.28) |
| Preterm | None | 1,399 (2.1) | 27/25,897 | 1.89 (1.28, 2.78) | 1.60 (1.07, 2.38) | 1.48 (1.00, 2.21) | 1.45 (0.97, 2.17) |
Model 1 is adjusted for age at first birth, age in 1989, race/ethnicity, and parental education
Model 2 is additionally adjusted for pre-pregnancy BMI, pre-pregnancy smoking, pre-pregnancy Alternative Healthy Eating Index (AHEI) score (in quintiles), pre-pregnancy alcohol intake, physical activity at age 18, and pre-pregnancy oral contraceptive use
Model 3 is additionally adjusted for pre-pregnancy chronic hypertension, pre-pregnancy hypercholesterolemia, pre-pregnancy type 2 diabetes mellitus, and family history of MI or stroke before age 60
Model 4 is additionally adjusted for parity at age 40
Sample size and total case numbers differ from those in Table 2 due to additional exclusion criteria: missing gestation length in the 2nd pregnancy on, reported gestation length <20 weeks and live birth, had a birth at age 40 or after, had an MI or stroke before age 40