The timing of onset of hypertensive disorders in pregnancy and the risk of incident hypertension and cardiovascular disease.

BACKGROUND: Previous studies suggest that women with hypertensive disorders of pregnancy (HDP) are at increased risk of subsequent cardiovascular disease (CVD). However, it is unclear whether this association differs by timing of onset of HDP.

METHODS: A population-based cohort of 146,748 women, aged 15-45 years, with a first recorded pregnancy were identified in the Clinical Practice Research Datalink. HDP were defined between 18 weeks gestation and 6 weeks postpartum and further sub-classified as early- (<34 weeks) and late-onset HDP (≥34 weeks). The primary outcome was incident CVD, and the secondary outcome was incident hypertension. We used marginal structural Cox models to account for time-varying exposure and confounding.

RESULTS: Compared with women with no HDP, those with early-onset HDP had a higher risk of developing incident CVD (HR 2.6, 95% CI 1.5, 4.3) and hypertension (HR 4.3, 95% CI 3.6, 5.0). Wide CIs precluded any conclusions regarding a difference in the risk of incident CVD and hypertension in women with early- vs late-onset HDP (HR 0.90, 95% CI 0.50, 1.62 and HR 1.06, 95% CI 0.87, 1.28, respectively).

CONCLUSION: HDP in at least one pregnancy was associated with an increased risk of subsequent CVD or hypertension, irrespective of time of diagnosis.