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 or 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, risks are much greater for mother and baby if hypertension is severe. This is also true if there are other conditions such as diabetes or if preeclampsia develops along with chronic hypertension.

Risks of severe chronic hypertension in pregnancy may include:

  • Blood pressure increasing

  • Heart failure

  • Bleeding in the brain

  • Kidney failure

  • 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)

  • Stillbirth

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 medicine. Your healthcare provider may switch you to a safer antihypertensive medicine 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 that uses sound waves to measure blood flow in babies with fetal growth restriction