Chronic Hypertension and Pregnancy
What is chronic hypertension?
Blood pressure is the force of the blood pushing against the artery walls. Each time the heart beats, it is pumping blood into these arteries. This results in the highest blood pressure when the heart contracts and is pumping the blood. High blood pressure, or hypertension, directly increases the risk of heart attack and stroke. Hypertension is defined in an adult as a blood pressure:
Greater than or equal to 140 mm Hg systolic pressure (Pressure is at its greatest when the heart contracts and is pumping the blood. This is called systolic pressure.)
Greater than or equal to 90 mm Hg diastolic pressure (When the heart is at rest, in-between beats, blood pressure falls. This is called diastolic pressure.)
When a woman has pre-existing hypertension or develops hypertension before the 20th week of pregnancy, this is called chronic hypertension.
Other forms of hypertension in pregnancy include preeclampsia. Preeclampsia is a serious condition with hypertension and problems with one ore more organs (for example the kidneys). Chronic hypertension increases the risk for preeclampsia.
How does pregnancy affect chronic hypertension?
Most risks are not increased for most women with mild chronic hypertension if there are no other complications. However, if hypertension is severe, if there are other conditions such as diabetes, or if preeclampsia develops along with chronic hypertension, risks are much greater for mother and baby.
Risks of severe chronic hypertension in pregnancy may include:
Blood pressure increasing
Bleeding in the brain
Placental abruption (early detachment of the placenta from the uterus)
Risks to the fetus and newborn depend on the severity of the disease and may include:
Fetal growth restriction -- decreased fetal growth due to poor placental blood flow.
Preterm birth (before 37 weeks of pregnancy)
Management of chronic hypertension during pregnancy
Prenatal care with careful monitoring of blood pressure are important. Women with high blood pressure often need to continue taking their antihypertensive medication. Your doctor may switch you to a safer antihypertensive medication while pregnant. A low-dose of daily aspirin may be recommended to help prevent complications.
Lab tests may be done on a regular basis to check the levels of various blood and urine substances related to hypertension. Other tests to monitor heart and kidney function may also be done. Fetal testing may begin in the second trimester and may include:
Ultrasound. Sound waves sent through a transducer are used to measure fetal growth.
Nonstress test. Measures fetal heart rate in response to fetal movement
Biophysical profile. A test that combines an ultrasound with the nonstress test
Doppler flow studies. A type of ultrasound which use sound waves to measure blood flow in babies with fetal growth restriction