Table 2.
Associations of paired pregnancy complications with CVD risk
| 95% CI* |
|||
|---|---|---|---|
| Combinations of pregnancy complications† |
HR‡ |
Lower |
Upper |
| SGA§ + preterm delivery | 2.6 | 1.06 | 6.20 |
| Gestational hypertension + hemoglobin decline | 2.8 | 1.15 | 6.92 |
| Pre-eclampsia∥ + SGA# | 3.7 | 1.12 | 12.10 |
| Preterm delivery (weeks 35-36) + hemorrhage | 3.9 | 1.63 | 9.56 |
| SGA + pre-existing hypertension | 4.8 | 1.78 | 12.91 |
| Gestational hypertension + preterm delivery# | 5.0 | 2.64 | 9.60 |
| Pre-eclampsia∥ + pre-existing hypertension | 5.6 | 2.09 | 15.18 |
| Preterm delivery + pre-existing hypertension | 7.1 | 3.49 | 14.55 |
CI=95% Confidence Interval (Lower limit, Upper limit)
Risk was estimated for each combination of pregnancy complications separately using a competing risks proportional hazards model. In order to avoid collinearity between paired pregnancy events, mutually exclusive dummy variables were included in each model. Using the first combination, SGA + preterm delivery as an example, three dummy variables were created to represent the following non-overlapping scenarios: 1) SGA only and not preterm delivery, 2) preterm delivery only and not SGA, and 3) SGA plus preterm delivery combined. The association for the co-occurrence of both events is tabled here. Models were adjusted for age, race and parity at study pregnancy. Age is represented continuously. Parity is represented using two dummy variables for primiparas and multiparas with 3 or more prior live births versus else.
HR=Hazard Ratio
SGA=small-for-gestational-age.
Early and late-onset pre-eclampsia were combined to maximize power for investigating the risk of pre-eclampsia co-occurring with other pregnancy events.
Co-occurring events involving pre-eclampsia, and preterm and SGA delivery were tested for age-dependence. Only the co-occurrence of gestational hypertension with preterm delivery and of pre-eclampsia with SGA were significantly age-dependent (p=0.0119 and p=0.0018 respectively). The hazard ratios for these paired events are estimated at age 60 for co-occurring gestational hypertension with preterm delivery, and at age 55 for co-occurring pre-eclampsia with SGA delivery.