Chronic hypertension may be diagnosed:

  • if you have hypertension before becoming pregnant; or
  • if your blood pressure before your 20th week is above 140 mmHg systolic or 90 mmHg diastolic on two occasions at least six hours apart.

If you are diagnosed with chronic hypertension, your doctor screens you for signs of superimposed preeclampsia throughout your pregnancy. Early signs of preeclampsia include excessive weight gain (more than five pounds a week) and protein in your urine (proteinuria). The diagnosis of superimposed preeclampsia is confirmed through testing a 24-hour urine sample for protein and blood tests to check for liver, kidney, or blood cell damage.

Your doctor may also ask whether you have experienced any of the symptoms of severe preeclampsia, including:

  • severe headaches;
  • blurred vision or seeing spots;
  • loss of appetite;
  • nausea or vomiting;
  • pain in right, upper abdomen; and
  • pain in the uterus or vaginal bleeding.
  • Assessing the Cause of Chronic Hypertension

Chronic hypertension may have no known cause ( essential hypertension ) or may be caused by underlying disease, such as kidney disease, thyroid disease, Cushing syndrome (high levels of cortisol which lead to hypertension), or connective-tissue disorders. It is important for your doctor to determine whether an underlying disorder is causing chronic hypertension since these disorders may pose additional risks to you and your baby. For example, diabetes increases the chances that the baby will be abnormally large ( macrosomia ), which can complicate delivery. If an underlying disorder is diagnosed, management focuses on treating the disorder.

Ninety percent of chronic hypertension cases during pregnancy have no known cause. The other 10% of cases are due to underlying disease. A list of possible causes of chronic hypertension is given in Table 1.

Table 1. Causes of Chronic Hypertension

  • Essential hypertension (90% of cases)

Vascular disorders

  • Renovascular hypertension

  • Aortic coarctation

Endocrine disorders

  • Diabetes mellitus

  • Hyperthyroidism

  • Pheochromocytoma

  • Primary hyperaldosteronism

  • Hyperparathyroidism

  • Cushing’s syndrome

Renal disorders

  • Diabetic nephropathy

  • Chronic renal failure

  • Acute Renal Failure

  • Tubular necrosis

  • Cortical necrosis

  • Pyelonephritis

  • Chronic glomerulonephritis

  • Nephrotic Syndrome

  • Polycystic kidney disease

Connective tissue disorders

  • Systemic lupus erythematosus

You doctor uses several methods to determine whether your hypertension is caused by an underlying disorder, including:

  • monitoring your blood pressure. In a sitting position, you will raise one arm to the level of your heart. This screens for conditions that cause blood pressure levels between the two sides of the body to differ, such as aortic coarctation (constriction of the aorta);
  • examining your eyes to look for typical findings of long-standing hypertension or diabetes in your retinas;
  • examining your thyroid gland for signs of an over- or under-active thyroid, which may contribute to hypertension;
  • examining your heart, skin, and joints;
  • screening for any abnormal skin lesions. Hypertension may be caused by conditions-including lupus erythematosus, scleroderma, or Cushing syndrome-that also cause skin problems; and
  • performing laboratory tests such as a complete blood cell count, urinalysis, and urine culture.

If your doctor suspects that you have chronic hypertension with superimposed preeclampsia, additional laboratory tests may be done to confirm the preeclampsia diagnosis and determine its severity.