Trends in using beta-blockers and methyldopa for hypertensive disorders during pregnancy in a Canadian population

Objective: To describe trends in and patterns of antihypertensive drug use in a general obstetric population.

Study design: Historical cohort study. A total of 18,117 women who gave birth in a Saskatchewan hospital between January 1, 1980 and December 31, 2005 with a diagnosis of hypertensive disorders in pregnancy were identified and included in the analysis.

Results: The rate of treatment with antihypertensive drugs for pregnant women with chronic hypertension rose from 19.94% in 1980-1984 to 37.63% in 2000-2005. There were similar increases in antihypertensive drug use from 1.51% to 14.47% for gestational hypertension/non-severe preeclampsia, and from 1.56% to 20.86% for severe preeclampsia/eclampsia. Methyldopa was the most frequently used drug, followed by beta-blockers, with other antihypertensive drugs accounting for about 18.43% of total uses. The use of both methyldopa and labetalol has increased in recent years while the use of other antihypertensive drugs has decreased. Other antihypertensive drugs were more commonly prescribed in earlier gestation, while methyldopa and labetalol were generally prescribed in later gestation.

Conclusion: The use of antihypertensive drugs in pregnancy is relatively common and is increasing, with the liberal use of methyldopa and (especially) labetalol contributing appreciably to this increase.