Essential hypertension in pregnancy: diagnosis, course and complications
THE CONTEXT
Essential hypertension is distinguished from pregnancy-associated hypertension by its earlier onset and persistence after delivery. Pregnancy may alter its course and increase complications.
Diagnostic features
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The listed diagnostic criteria include blood pressure of at least 140/90 mm Hg before the 20th week of pregnancy, with molar pregnancy excluded.
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Other listed criteria are cardiac enlargement on chest radiograph and ECG, the presence of medical disorders and persistent blood pressure elevation beyond 42 days after delivery.
Distinction from other hypertensive disorders
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Essential hypertension is associated with prepregnancy hypertension and onset before 20 weeks. Pre-eclampsia begins after 20 weeks, while gestational hypertension usually begins in the third trimester.
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Proteinuria is present in pre-eclampsia, absent in gestational hypertension and usually absent in essential hypertension.
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The comparison table describes complete resolution of blood pressure elevation in pre-eclampsia and gestational hypertension, whereas essential hypertension persists even beyond 3 months after delivery.
Effect of pregnancy on hypertension
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About 50% may have a midpregnancy fall in blood pressure, followed by a rise in the last trimester that may or may not reach the previous level.
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In 50%, blood pressure rises progressively as pregnancy advances.
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Pre-eclampsia is superimposed in about 20%. New proteinuria exceeding 300 mg/24 hours or a protein/creatinine ratio above 0.3 is described as a rare development.
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Permanent deterioration of hypertension after delivery occurs in 30%.
Effect on pregnancy
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Maternal risk remains unaltered in milder disease but maternal and perinatal risks increase substantially with severe disease or superimposed pre-eclampsia.
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The complications listed include placental abruption and fetal growth restriction.