Synergistic Effect of Gestational Hypertension and Postpartum Incident Hypertension on Cardiovascular Health: A Nationwide Population Study

BACKGROUND Gestational hypertension (GH) is a common complication of pregnancy and is associated with increased risk of incident hypertension in later life (IH) and cardiovascular events. However, the interactive effect of GH and IH on postpartum cardiovascular health remains unclear. METHODS AND RESULTS A nationwide population-based study was conducted using 1 million individuals from the Taiwan National Health Insurance database. Records from 1998 to 2009 were used to identify 1260 pregnant women with GH and without previous cardiovascular disease. The control group comprised 5040 pregnant women without GH, matched for age and date of delivery. During the follow-up period (median duration, 5.8 years), 182 cardiovascular events developed. Women with GH had significantly higher risk of cardiovascular events (hazard ratio [95% CI], 2.44 [1.80 to 3.31]) and IH (8.29 [6.30 to 10.91]) than controls. Compared with women without GH and IH, there was a significantly higher risk of cardiovascular events for women without GH but with IH (relative risk [95% CI], 2.89 [1.27-6.58]), women with GH but without IH (1.66 [1.16-2.39]), and women with GH and IH (8.11 [5.36-12.30]). The synergy index was 2.91 (95% CI 1.11 to 7.59), suggesting a positive interaction between GH and IH. CONCLUSIONS GH increased the risk of subsequent IH. Women with both GH and IH were at a substantially higher cardiovascular risk than were women with either GH or IH. The synergistic adverse effect of GH and IH on postpartum cardiovascular health indicates that more attention should be paid to this special population.