Seven of every 100 women are affected by high blood pressure, or hypertension, during pregnancy and most did not have a previous history of this condition. Elevated blood pressure that develops for the first time during pregnancy, especially after week 20, is called pregnancy induced hypertension (PIH).
The risk of PIH is greatest in women who've had it during previous pregnancies, who are pregnant for the first time, who have diabetes or kidney disease, are older than age 40, or are carrying more than one fetus.
A blood pressure reading of 140/90 (or above) is considered too high during pregnancy. The higher number, or systolic pressure, is created by the contraction of the heart muscle; the lower number, diastolic pressure, reflects arterial resistance when the heart muscle relaxes between beats. Your doctor should check your blood pressure at each prenatal visit, but you also should get prompt medical attention if you notice any of these possible warning signs of high blood pressure during pregnancy:
If you have high blood pressure before pregnancy and take medication for it, you'll be relieved to hear that most medications for this disorder are safe to use during pregnancy, under your doctor's care. There is, however, an important exception: a class of medications called angiotensin-converting enzyme (ACE) inhibitors. ACE inhibitors are generally avoided during pregnancy, especially late pregnancy. If you are planning to become pregnant and are taking an ACE inhibitor, see your doctor to switch to another medicine. If you are taking an ACE inhibitor and find out you are pregnant, call your doctor so he or she can switch you to another medicine as soon as possible. Be sure to ask both your doctor and your gynecologist about any medications you're using well before you plan to get pregnant, in case a change is indicated.
Mild hypertension that's kept under control usually will not harm you or your baby. Severe hypertensive complications of pregnancy, however, can damage your vital organs, including eyes, kidneys, heart, brain and liver; or may even be life threatening to you and your child. In the most extreme cases, it can cause seizures, premature birth or even fetal death. To protect your health, in a severe case, it may be necessary for your obstetrician to induce early delivery, even if your baby will be born very small.
Less severe cases may be treated with bed rest, either at home or in a hospital. If your pressure doesn't rise to dangerous levels, you should be able to give birth naturally, at term. For more on this topic, send a stamped self-addressed envelope to the American College of Obstetrics and Gynecology, 409 Twelfth St., SW; Washington, DC 20024 and request its free pamphlet, High Blood Pressure During Pregnancy.