REPORT OF THE CANADIAN-HYPERTENSION-SOCIETY-CONSENSUS-CONFERENCE .3. PHARMACOLOGICAL TREATMENT OF HYPERTENSIVE DISORDERS IN PREGNANCY

Objective: To provide Canadian physicians with evidence-based guidelin es for the pharmacologic treatment of hypertensive disorders in pregna ncy. Options: No medication, or treatment with antihypertensive ol ant iconvulsant drugs. Outcomes: Prevention of maternal complications, and prevention of perinatal complications and death. Evidence: Pertinent articles published from 1962 to September 1996 retrieved from the Preg nancy and Childbirth Module of the Cochrane Database of Systematic Rev iews and from MEDLINE; additional articles retrieved through a manual search of bibliographies; and expert opinion. Recommendations were gra ded according to levels of evidence. Values: Maternal and fetal well-b eing were equally valued, with the belief that treatment side effects should be minimized. Benefits, harms and costs: Reduction in the rate of adverse perinatal outcomes, including death. Potential side effects of antihypertensive drugs include placental hypoperfusion,intrauterin e growth retardation and long-term effects on the infant. Recommendati ons: A systolic blood pressure greater than 169 mm Hg or a diastolic p ressure greater than 109 mm Hg in a pregnant woman should be considere d an emergency and pharmacologic treatment with hydralazine, labetalol or nifedipine started. Otherwise, the thresholds at which to start an tihypertensive treatment are a systolic pressure of 140 mm Hg or a dia stolic pressure of 90 mm Hg in women with gestational hypertension wit hout proteinuria or pre-existing hypertension before 28 weeks' gestati on, those with gestational hypertension and proteinuria or symptoms at any time during the pregnancy, those with pre-existing hypertension a nd underlying conditions or target-organ damage, and those with pre-ex isting hypertension and superimposed gestational hypertension. The thr esholds in other circumstances are a systolic pressure of 150 mm Hg or a diastolic pressure of 95 mm Hg. For nonsevere hypertension, methyld opa is the first-line drug; labetalol, pindolol, oxprenolol and nifedi pine are second-line drugs. Fetal distress attributed to placental hyp operfusion is rare, and long-term effects on the infant are unknown. M agnesium sulfate is recommended for the prevention and treatment of se izures. Validation: The guidelines are more precise but compatible wit h those from the US and Australia.