(BSPOT20) Prevalence and treatment of chronic hypertension during pregnancy in a U.S. cohort, 2008-2021

Background: Treatment of chronic hypertension during pregnancy has been shown to reduce the risk of adverse perinatal outcomes.

Objectives: In this study, our objectives were to examine the patterns of use of antihypertensive medications among pregnant individuals with chronic hypertension, and to assess the impact of the updated 2017 hypertension guidelines of the American College of Cardiology and American Heart Association (ACC/AHA) on the prevalence and treatment of chronic hypertension during pregnancy.

Methods: We analyzed the MerativeTM Marketscan® Research Database of commercial insurance claims in the United States from 2007 to 2021. We included individuals with continuous enrollment from three months prior to pregnancy through delivery. We used International Classification of Diseases-Clinical Modification (ICD-CM), 9th and 10th Revisions, diagnosis codes assigned between 90 days prior to through 140 days after the estimated last menstrual period to identify cases of chronic hypertension (ICD-9-CM: 401, 642.0, 642.7; ICD-10-CM: I10, O10.0, O11). We identified oral antihypertensive medications dispensed by outpatient pharmacies using a previously established list of medications. We performed interrupted time series analyses to assess whether the 2017 ACC/AHA hypertension guidelines increased the proportion of individuals diagnosed with chronic hypertension or treated with oral antihypertensive medications during pregnancy.

Results: The prevalence of chronic hypertension steadily increased from 1.8% to 3.7% among 1,900,196 pregnancies between 2008 and 2021. Medication use for chronic hypertension in pregnancy was relatively stable (57-60%) over the study period, and varied modestly among subpopulations with high-risk comorbidities (56-67%). The proportion of pregnant individuals with chronic hypertension treated with methyldopa or hydrochlorothiazide decreased over the study period (from 29% to 2% and from 11% to 5%, respectively), while the proportion treated with labetalol or nifedipine increased (from 19% to 42% and from 9% to 17%, respectively). The prevalence or treatment of chronic hypertension during pregnancy did not change following the 2017 ACC/AHA hypertension guidelines.

Conclusions: The prevalence of chronic hypertension in pregnancy doubled between 2008 and 2021 in this nationwide cohort of individuals with commercial insurance. During the study period, labetalol replaced methyldopa as the most commonly used antihypertensive. However, only about 60% of patients with chronic hypertension in pregnancy were treated with antihypertensive medications.