(289) Patterns of prescribing antihypertensive medications during pregnancy in the UK

Background: Pregnancy hypertension, encompassing chronic and gestational hypertension, affects approximately 10% of pregnant women and is associated with adverse maternal and perinatal health outcomes. National guidelines recommend labetalol, nifedipine, and methyldopa for use during pregnancy due to contraindications or limited safety data for other agents.

Objectives: Our study aims to describe the prescribing patterns of antihypertensive medications during pregnancy in the UK and compare them with current guidelines.

Methods: We conducted a descriptive study of a pregnancy cohort, using electronic health records from the UK Clinical Practice Research Datalink (CPRD) Gold and Aurum from 2000 to 2021. We identified completed pregnancies and included women linked to CPRD Pregnancy Register who were registered in the database at least 12 months before the last menstrual period to 3 months post-delivery. We assessed the prescriptions of antihypertensive medications by therapeutic class in the 3 months pre-pregnancy period and each trimester. For those using antihypertensive medications before pregnancy, we investigated prescribing patterns during the first and second trimesters, including whether they continued with their pre-pregnancy medication, discontinued pharmacotherapy, or switched to recommended treatments, such as labetalol, nifedipine, or methyldopa.

Results: We identified 3,781,966 pregnancy episodes, of which 60,263 (1.6%) involved exposure to antihypertensive medications during pregnancy. Pregnant women using antihypertensive medications were older with mean age of 33±6 years compared to 30±6 years for non-users. The prescription rates during pregnancy were 1.1% in the first trimester, 0.5% in the second trimester, and 0.7% in the third trimester. Beta-blockers were the most commonly prescribed class during the first trimester (45%), whereas labetalol dominated during the second trimester (37%) and third trimester (46%). Among individuals who took antihypertensives before pregnancy, during the first trimester, 45% continued their medications, 42% discontinued, 9% switched to recommended treatments, and 4% switched to other antihypertensives. By the second trimester, 29% continued, 56% discontinued, 10% switched to recommended treatments, and 5% switched to other antihypertensives.

Conclusions: In this population of UK pregnant women, a wide range of antihypertensive agents were prescribed during pregnancy with recommended treatments being predominant. However, some patients continued contraindicated drugs throughout pregnancy. Future studies are needed to assess the safety and effectiveness of these medications.