If your blood pressure is consistently higher than 150/100 during your pregnancy or if you have high levels of protein in your urine or other evidence that your kidneys aren't functioning properly, you may be at high risk for serious complications of hypertension, including heart attack or stroke. You may require medication to lower your blood pressure and protect you against these complications. If your blood pressure is higher than 180/120--dangerously high--you may require intravenous medication to bring your blood pressure down immediately.
If your case is not severe, whether or not medication to control high blood pressure should be given is a controversial issue. Although it may be beneficial to the mother, lowered pressure may decrease blood flow to the placenta and jeopardize the health of the baby. The National High Blood Pressure Education Program Working Group (1990) concluded that the data on whether to treat chronic hypertension in pregnant women with normal blood pressure was too limited to make treatment guidelines. The group did, however, recommend medical therapy to control high blood pressure when maternal diastolic blood pressure reaches 100 mm Hg or 90mm Hg if the mother has severe complications from hypertension.