Hypertensive Disorders in Pregnancy( a quick review)

Hypertensive disorders of pregnancy can be classified as:

1. Gestational hypertension (formerly PIH or transient hypertension)

2. Pre-eclampsia and eclampsia

3. Pre-eclampsia superimposed on chronic hypertension

4. Chronic hypertension.

Gestational hypertension: It is said to be present when BP > 140/90 mm Hg for first time during pregnancy after 20 weeks, but no proteinuria. This is transient hypertension and blood pressure returns to normal by 12 weeks postpartum.

Pre-eclampsia: It is defined as new hypertension presenting after 20 weeks with significant proteinuria [more than 300 mg per 24 hours, or persistent 30 mg/dL (1+ on dipstick)] in random urine samples.

Chronic hypertension: BP > 140/90 mm Hg before pregnancy or diagnosed before 20 weeks gestation or hypertension first diagnosed after 20 weeks of gestation and persistent after 12 weeks postpartum.

Superimposed pre-eclampsia (on chronic hypertension): All chronic hypertensive disorders regardless of their cause predispose to development of superimposed pre-eclampsia or eclampsia. Pre-eclampsia is accompanied by proteinuria.

The pathogenesis of pre-eclampsia

Theories for development of pre-eclampsia:

1.     Increased pressor responses: Women with PIH have been found to have increased vascular sensitivity to pressors.

2.     Prostaglandins: In PIH, there is decreased prostacyclin production and increased thromboxane A2; resulting in vasoconstriction and sensitivity to infused Angiotensin II.

3.Nitric oxide Decreased levels are found in PIH patients.

4. Vascular endothelial growth factor (VEGF):

VEGF has been reported to be increased in serum from women with pre-eclampsia.

5. Genetic predisposition

6. Immunological factors: PIH is probably an immune response to antigenic sites on placenta.

7.Inflammatory factors: Pre-eclampsia is considered a disease due to extreme state of activated leukocytes in the maternal circulation.