Chronic hypertensive disease in pregnancy: definition and risk factors
THE CONTEXT
Chronic hypertensive disease is distinguished by hypertension predating pregnancy or appearing before 20 weeks and persisting beyond 12 weeks after delivery.
Definition and frequency
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Chronic hypertensive disease includes hypertension of any cause antedating pregnancy or present before the 20th week, with persistence beyond 12 weeks after delivery.
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Diagnosis and management are difficult when the condition is first encountered beyond the 20th week of pregnancy.
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The overall incidence is 2–4%; 90% of cases are due to essential hypertension.
High-risk features
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High-risk features include age over 40 years, hypertension lasting more than 15 years and blood pressure above 160/110 mm Hg.
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Renovascular or collagen vascular disease and the presence of thrombophilias are additional high-risk features.
Outcome
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Most women with chronic hypertensive disease are low-risk and have satisfactory maternal and fetal outcomes without antihypertensive therapy.
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The overall risk of superimposed pre-eclampsia is 25%.