Considerations about blood pressure readings during pregnancy

Blood pressure is always monitored closely during pregnancy. Your blood pressure is measured during pregnancy at every prenatal visit, and you can also monitor it at home. Rapidly increasing or abnormally high blood pressure can be a sign of preeclampsia. Severe high blood pressure can be dangerous to both you and your fetus.

During pregnancy, blood pressure normally stays at prepregnancy levels during the first trimester, then drops slightly in the second trimester. It rises to prepregnancy levels in the third trimester.

If you have chronic high blood pressure (hypertension), your blood pressure during pregnancy will probably remain at or slightly below your prepregnancy level.

Consider the following about blood pressure elevation and preeclampsia during pregnancy:

• Mild and moderate high blood pressure (140/90 up to 179/109 mm Hg) usually does not cause any symptoms and cannot be detected unless blood pressure is measured. However, because an increase in blood pressure can be a first sign of preeclampsia, you will be closely monitored if you have elevated blood pressure.
• An increase in blood pressure of 30 mm Hg systolic or 15 mm Hg diastolic that can be duplicated at least 6 hours later, especially in the third trimester, is cause for concern. This may indicate previously undiagnosed chronic high blood pressure or mild preeclampsia. It may be unclear which condition is causing the increase in blood pressure, even after several weeks.
• When preeclampsia is suspected or diagnosed, frequent measurements of blood pressure, urine screens for protein, and blood tests are necessary at home, in the doctor's office, or in the hospital.