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Gestational hypertension is a hypertensive disorder that develops about halfway through pregnancy. It occurs in about 5 to 8 percent of all pregnancies and usually goes away after pregnancy. If it does not, the diagnosis is changed to chronic hypertension.
Gestational hypertension can develop into preeclampsia. This condition occurs most 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 after 20 weeks of pregnancy with normal blood pressure.
Preeclampsia (also known as toxemia) 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).
Why is gestational hypertension a concern?
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 gestational hypertension. 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 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.