Gestational hypertension is a form of high blood pressure in pregnancy. It occurs in about 6 percent of all pregnancies. Another type of high blood pressure is chronic hypertension--high blood pressure that is present before pregnancy begins. Gestational hypertension can develop into preeclampsia. This condition occurs often in young women with a first pregnancy. It is more common in twin pregnancies, in women over the age of 35, in women with chronic hypertension or who had hypertension in a previous pregnancy, in African-American women, and in women with diabetes. Gestational hypertension is diagnosed when blood pressure readings are higher than 140/90 mm Hg in a woman who had normal blood pressure prior to 20 weeks and has no proteinuria (excess protein in the urine). Preeclampsia is diagnosed when a woman with gestational hypertension also has increased protein in her urine. Eclampsia is a severe form of preeclampsia. Women with eclampsia have seizures resulting from the condition. Eclampsia occurs in about one in 1,600 pregnancies and develops near the end of pregnancy, in most cases. HELLP syndrome is a complication of severe preeclampsia or eclampsia. HELLP syndrome is a group of physical changes including the breakdown of red blood cells, changes in the liver, and low platelets (cells found in the blood that are needed to help the blood to clot in order to control bleeding).

The cause of gestational hypertension is unknown. Some conditions may increase the risk of developing the condition, including the following:

• Pre-existing hypertension (high blood pressure)
• Kidney disease
• Diabetes
• Hypertension with a previous pregnancy
• Mother's age younger than 20 or older than 40
• Multiple fetuses (twins, triplets)
• African-American race

With high blood pressure, there is an increase in the resistance of blood vessels. This may hinder blood flow in many different organ systems in the expectant mother including the liver, kidneys, brain, uterus, and placenta. There are other problems that may develop as a result of severe gestational hypertension (blood pressure readings that are higher than 160/110 mm Hg).  Placental abruption (premature detachment of the placenta from the uterus) may occur in some pregnancies. Gestational hypertension can also lead to fetal problems including intrauterine growth restriction (poor fetal growth) and stillbirth. If untreated, severe gestational hypertension may cause dangerous seizures (eclampsia) and even death in the mother and fetus. Because of these risks, it may be necessary for the baby to be delivered early, before 37 weeks gestation.

The following are the most common symptoms of high blood pressure in pregnancy. However, each woman may experience symptoms differently, and a patient with gestational hypertension may be completely asymptomatic. Symptoms may include:

• Increased blood pressure
• Absence or presence of protein in the urine (to diagnose gestational hypertension or preeclampsia)
• Edema (swelling)
• Sudden weight gain
• Visual changes such as blurred or double vision
• Nausea, vomiting
• Right-sided upper abdominal pain or pain around the stomach
• Urinating small amounts
• Changes in liver or kidney function tests

Diagnosis is often based on the increase in blood pressure levels, but other symptoms may help establish gestational hypertension as the diagnosis. Tests for gestational hypertension may include the following:

• Blood pressure measurement
• Urine testing to rule out preeclampsia
• Assessment of edema
• Frequent weight measurements
• Liver and kidney function tests to rule out preeclampsia
• Blood clotting tests to rule out preeclampsia

Specific treatment for gestational hypertension will be determined by your doctor based on:

• Your pregnancy, overall health, and medical history
• Extent of the disease
• Your tolerance for specific medications, procedures, or therapies
• Expectations for the course of the disease
• Your opinion or preference

The goal of treatment is to prevent the condition from becoming worse and to prevent it from causing other complications. Treatment for gestational hypertension may include:

• Bedrest, either at home or in the hospital, may be recommended
• Hospitalization (as specialized personnel and equipment may be necessary)
• Magnesium sulfate (or other antihypertensive medications for gestational hypertension if blood pressure readings are in the severe range)
• Fetal monitoring (to check the health of the fetus) which may include:
  • Fetal movement counting. Keeping track of fetal kicks and movements. A change in the number or frequency may mean the fetus is under stress.
  • Nonstress testing. A test that measures the fetal heart rate in response to the fetus's movements.
  • Biophysical profile. A test that combines nonstress test with ultrasound to observe the fetus.
  • Doppler flow studies. A type of ultrasound that uses sound waves to measure the flow of blood through a blood vessel.
• Continued laboratory testing of urine and blood (for changes that may signal worsening of gestational hypertension or progression to preeclampsia)
• Medications, called corticosteroids, that may help to mature the lungs of the fetus (lung immaturity is a major problem of premature babies).

Early identification of women at risk for gestational hypertension may help prevent some complications of the disease. Education about the warning symptoms is also important because early recognition may help women receive treatment and prevent worsening of the disease.