(P284) USE OF ANTIHYPERTENSIVE MEDICATIONS IN THE ANTEPARTUM AND POSTPARTUM PERIODS: OBSERVATIONS FROM A COHORT OF HYPERTENSIVE PREGNANT PATIENTS AT A CANADIAN TERTIARY CENTRE

Background: The management of hypertension in pregnancy fundamentally focuses on safely prolonging pregnancy to achieve greater fetal maturity by maintaining acceptable maternal blood pressure levels. Current Canadian practice guidelines recommend a range of antihypertensive medications with widely differing actions. The objective of this investigation was to determine current patterns of antihypertension medication use at a tertiary maternity referral centre during the antepartum and immediate postpartum periods in pregnant patients.

METHODS AND RESULTS: We conducted a retrospective cohort study of 1,085 pregnant patients with hypertensive disorders of pregnancy that delivered at Mount Sinai Hospital, Toronto, Canada from March 2017 – December 2020. Maternal demographics were collected from the electronic medical records system, as well as maternal, perinatal and pregnancy outcomes. In this cohort of 1,085 hypertensive pregnant patients, median maternal age was 35 years old [31-38], and 56% of patients were nulliparous. The majority of this cohort had new-onset hypertension, with 224 (21%) reporting prior chronic hypertension. 593 patients were diagnosed with preeclampsia, while 492 were diagnosed with gestational hypertension. Median gestational age at delivery was 36 weeks [32-38], with median Intergrowth birthweight centile of 30 [8-65]. In the antepartum period, 708 patients (65%) were prescribed an antihypertensive agent, of which 463 were prescribed two or more antihypertensive agents. Labetalol was the most commonly prescribed antihypertensive agent (640 patients), followed by long-acting nifedipine (439 patients) and short-acting nifedipine (280 patients). Following delivery, 593 patients (55%) were discharged with a prescription for an antihypertensive agent, of which 276 patients were prescribed more than 1 antihypertensive agent. 435 patients were discharged with a higher number of prescriptions for antihypertensive agents relative to before delivery. In the immediate postpartum period following discharge, 58 patients presented to our Obstetric triage with hypertension concerns; 25 of these patients were readmitted to hospital.

Conclusion: These findings reflect the patient journey through care for hypertension in pregnancy and illustrate the need for continued specialized cardiovascular care in the postpartum period for hypertensive patients.