Persistent Hypertension After Pregnancy

Persistent hypertension after pregnancy is blood pressure of 140/90 mmHg or more that remains at 12 weeks or more after delivery, showing chronic hypertension that was either pre-existing or unmasked by pregnancy. It follows some hypertensive pregnancies. It matters because women with preeclampsia have a higher lifetime risk of hypertension, stroke and heart disease.

• Risk factors: severe or early onset preeclampsia, recurrent preeclampsia, obesity, family history, kidney disease, diabetes.
• Secondary causes must be sought in young women.
• Planning for the next pregnancy needs drug changes before conception.

Most women have no symptoms. Others have headache, palpitations or tiredness. Examine blood pressure in both arms, weight, heart, renal bruits and fundi.

• Blood pressure 140/90 mmHg or more at 12 weeks postpartum.
• Left ventricular hypertrophy in long-standing disease.
• Differential diagnosis: essential hypertension, chronic kidney disease, renal artery stenosis, primary aldosteronism, phaeochromocytoma, Cushing syndrome, coarctation, thyroid disease, oral contraceptive effect, obstructive sleep apnoea.
• Complications: stroke, ischaemic heart disease, heart failure, kidney disease, retinopathy, superimposed preeclampsia in later pregnancy.

The diagnosis is confirmed by repeated readings with assessment for causes and organ damage.

• Home blood pressure for 7 days or 24 hour ambulatory monitoring (average 135/85 mmHg or more confirms).
• Creatinine, estimated glomerular filtration rate, electrolytes, urine protein to creatinine ratio, urinalysis, fasting glucose or HbA1c, lipid profile, TSH.
• ECG, echocardiography, fundoscopy; renal ultrasound.
• Aldosterone to renin ratio, plasma metanephrines and renal artery imaging when blood pressure is resistant, there is hypokalaemia, or onset is below 40 years.

The principle is lifestyle change and drug treatment to a target below 140/90 mmHg (below 130/80 mmHg in diabetes or kidney disease), with attention to contraception and the next pregnancy.

• Supportive: weight loss to a body mass index below 25 kg/m2; salt below 5 g daily; regular exercise 150 minutes weekly; stop smoking; limit alcohol; contraception without oestrogen; annual cardiovascular risk review.
• Pharmacological: enalapril 5 mg oral once daily increased to 20 mg (maximum 40 mg), or amlodipine 5 mg oral once daily increased to 10 mg, or hydrochlorothiazide 12.5 mg oral once daily increased to 25 mg, adding a second drug if blood pressure remains 140/90 mmHg or more after 4 weeks; atorvastatin 20 mg oral at night for raised lipids after breastfeeding ends and with reliable contraception; metformin 500 mg oral twice daily increased to 1 g twice daily for diabetes; before another pregnancy change enalapril to labetalol 200 mg oral every 8 to 12 hours (maximum 2.4 g daily) or nifedipine modified release 30 to 60 mg oral once daily (maximum 120 mg), and start aspirin 150 mg oral at night from 12 weeks to 36 weeks.
• Procedures: renal artery angioplasty or adrenal surgery for secondary causes where found.
• Special groups: breastfeeding is compatible with enalapril, amlodipine, nifedipine and labetalol and not with hydrochlorothiazide at high doses; ACE inhibitors and angiotensin receptor blockers are stopped before conception or when pregnancy is confirmed; diabetes or kidney disease needs enalapril with monitoring of creatinine and potassium after 2 weeks.
• Red flags: blood pressure 180/110 mmHg or more, chest pain, breathlessness, visual loss, focal weakness, rising creatinine, potassium below 3.5 mmol/L.
• Follow-up: blood pressure review every 4 weeks until controlled, then every 3 to 6 months; annual creatinine, urine protein, glucose and lipids; preconception review before any future pregnancy.