Pregnancy and Hypertension

HYPERTENSION IS A MAJOR MEDICAL COMLICATION IN 15-20% OF PREGNANCIES.

Untreated or poorly managed hypertension in pregnancy may result in fatal consequences for the mother and fetus. Hypertension in pregnancy is defined as systolic blood pressure greater than 140mmhg or a diastolic blood pressure greater than 90mmhg at any time during pregnancy. Studies have shown that one in five women have hypertension after being pregnant for over 20 weeks. Healthcare professionals monitor the blood pressure of pregnant women closely (usually in the sitting position) because, some women develop elevated blood pressure for the first time while pregnant.

Pregnant women with hypertension are grouped in to 3 broad categories:

• Chronic hypertension- this is a leading cause of hypertension worldwide. The forms of hypertension could be either primary (commoner) or secondary. Identifiable risk factors of chronic hypertension include a prior history of hypertension, insulin resistance and obesity.
• Pregnancy induced hypertension or Gestational hypertension- is defined as hypertension occurring in the latter half of pregnancy (after 20 weeks in a woman with no prior history of hypertension) and associated with:

1. The absence of protein in the urine,

2. Absence of signs and symptoms that characterize Preeclampsia (see below).

• Preeclampsia- is a hypertensive disorder associated with loss of protein in urine (proteinuria), swelling of the ankles and legs (edema) and occasionally, blood coagulation and liver function abnormalities. It is defined as a systolic blood pressure > 140mmhg and a diastolic blood pressure > 90mmhg in a woman with normal blood pressure before a 20 week pregnancy. Preeclampsia occurs in 5-10% of pregnancies and its cause is unknown. However, poor blood flow to the placenta has been identified as fundamental to the disease process. Risk factors for preeclampsia include a family history of pre-eclampsia, obesity, diabetes mellitus, preeclampsia in a prior pregnancy, first pregnancy, kidney disease of any cause, pregnancy at age over 40 years and a multiple pregnancy.

  Preeclampsia may progress to Eclampsia, a clinical state characterized by convulsions (also known as seizures or fits) brought about by brain involvement.

Your healthcare professional will determine if you are at risk of hypertension. This evaluation should begin prior to conception and include:

• Identification of risk factors
• Identification of existing hypertension (essential or secondary)

In addition several laboratory tests (e.g urinalysis and blood chemistry) are mandatory to assist in the diagnosis of hypertension before and during pregnancy. A Doppler ultrasound scan may be necessary to determine the level of blood flow to the placenta. Women with longstanding hypertension, diabetes mellitus, kidney disease, heart disease, severe hypertension early in pregnancy, and a history of miscarriages require closer monitoring. Prescription medication may be required to maintain clinically acceptable levels of hypertension. Anti-hypertensive therapy should be commenced if systolic blood pressure is > 140 mmhg. Either hydralazine or labetalol (a combined alpha and beta receptor antagonist) can be used as first line drugs, although labetalol is preferable. Women with suspected pre-ecclampsia should be hospitalized and clinically evaluated. For pregnancies near to term, delivery remains the treatment of choice for pre-eecclampsia as long as fetal viability is assured. Pre-eclampsia occurring earlier in pregnancy requires effective control of blood pressure, laboratory and clinical assessment and ensuring that the fetus reaches a viable age before delivery is considered. Convulsions or fits resulting from ecclampsia usually resolve as spontaneously as they begin, however anti-convulsive therapy should be given to abort the seizures when possible. Magnesium sulfate (preferred) or diazepam can be used to control such fits. Magnesium sulfate can also be used to prevent further fits in cases of established eclampsia.