Hypertensive disorders in pregnancy are major contributors to maternal and perinatal morbidity and mortality, affecting 10% of all pregnant women. Hypertension most often appears for the first time in women who have had normal blood pressure before pregnancy and may be associated with proteinuria and convulsions. The causes of hypertension in pregnancy are still largely unknown.

Hypertensive disorders in pregnancy include:

Hypertension is diagnosed when the systolic blood pressure is ≥140 mmHg and/or the diastolic blood pressure is ≥ 90 mmHg on two consecutive readings taken 4 hours or more apart. A time interval of less than 4 hours is acceptable if urgent delivery must take place, or if the diastolic blood pressure is equal to or greater than 110 mmHg.

Diastolic blood pressure is a good indicator of prognosis for the management of hypertensive diseases in pregnancy. Diastolic blood pressure is taken at the point the arterial sound disappears. A falsely high reading is obtained when the inflatable part of the cuff does not encircle at least three-quarters of the circumference of the arm. Use a wider cuff when the width of the upper arm is more than 30 cm.

Hypertension is classified as pregnancy induced hypertension if it occurs for the first time:

If it occurs before 20 weeks of gestation, it is classified as chronic hypertension. If the blood pressure prior to 20 weeks of gestation is unknown, differentiation may be impossible; in this case, manage as pregnancy induced hypertension.

The presence of proteinuria changes the diagnosis from pregnancy induced hypertension to pre-eclampsia.

Other conditions that cause proteinuria or false positive results include:

Only clean catch mid-stream specimens should be used for testing. Catheterization for the sole purpose of testing is not justified due to the risk of urinary tract infection.

Clinical features

Pregnancy induced hypertension is more common among women who are pregnant for the first time. Women with multiple pregnancies, diabetes and underlying vascular problems are at higher risk of developing pregnancy induced hypertension. The spectrum of the disease includes:

Women with pregnancy-induced hypertensive disorders may progress from mild disease to a more serious condition. Mild pre-eclampsia is often symptomless. Rising blood pressure may be the only clinical sign. A woman with hypertension may feel perfectly well until seizure suddenly occurs.

Proteinuria is a later manifestation of the disease process. When pregnancy induced hypertension is associated with proteinuria, the condition is called pre-eclampsia. Increasing proteinuria is a sign of worsening pre-eclampsia. Mild pre-eclampsia could progress to severe pre-eclampsia; the rate of progression could be rapid. The risk of complications, including eclampsia, increases greatly in severe pre-eclampsia.

Eclampsia

Eclampsia is characterized by convulsions, together with signs of pre-eclampsia. Convulsions can occur regardless of severity of hypertension, are difficult to predict and typically occur in the absence of hyperreflexia, headache or visual changes. Convulsions are tonic-clonic and resemble grand-mal seizures of epilepsy. Seizures may recur in rapid sequence, as in status epilepticus, and end in death. Convulsion may be followed by coma that lasts minutes or hours, depending on the frequency of seizures. 25% of eclamptic fits occur after delivery of the baby.

Eclampsia must be differentiated from other conditions that may be associated with convulsions and coma, including epilepsy, cerebral malaria, head injury, cerebrovascular accident, intoxication (alcohol, drugs, poisons), drug withdrawal, metabolic disorders, meningitis, encephalitis, hypertensive encephalopathy, water intoxication and hysteria.

In general, convulsions in a woman who is pregnant or has been recently delivered (within 48 hours after delivery) should be managed as eclampsia, unless proved otherwise.