Blood Pressure 15 to 90 Days After a Hypertensive Disorder of Pregnancy and Later Hypertension

BACKGROUND: Timely diagnosis of hypertension provides an opportunity for cardiovascular disease prevention after a hypertensive disorder of pregnancy. We assessed the association between blood pressure 15 to 90 days postpartum and incident hypertension after a hypertensive disorder of pregnancy. METHODS: This was a retrospective cohort study of women with no preexisting hypertension and a hypertensive disorder of pregnancy between January 2014 and December 2017 at 2 health systems in the southeastern United States. Cox proportional hazards models assessed the association of postpartum blood pressure and incident hypertension over a median follow-up period of 9.9 months. Covariates selected via directed acyclic graph construction included type of hypertensive disorder, race, ethnicity, maternal age, smoking, body mass index, and gestational diabetes. RESULTS: Out of 5657 women, only 2520 (45%) met the inclusion criteria; 39% (1584) of otherwise eligible individuals did not have a blood pressure check at 15 to 90 days postpartum. The hazards of incident hypertension during follow-up were significantly higher for those with higher systolic postpartum blood pressure (1.81 95% CI, 1.46-2.24). The estimated cumulative incidence of hypertension over the first 12 months of follow-up among participants with a blood pressure of 110/65 mm Hg was 4.5% (95% CI, 2.8%-6.1%), and with blood pressure 140/90, it was 12.0% (95% CI, 8.4%-17.2%). CONCLUSIONS: The risk of incident hypertension after a hypertensive disorder of pregnancy is high in the first year postpartum especially for those with elevated systolic blood pressure postpartum. Despite this, for many participants, blood pressure was not measured within 15 to 90 days postpartum.