High Blood Pressure And The Fetus
High blood pressure that is present before a pregnancy or develops during pregnancy can put your baby at risk. High blood pressure increases the risk of delivering a low birth weight baby or delivering a baby prematurely. If long-standing high blood pressure has damaged the mother’s kidneys, there is a higher risk of miscarriage or fetal death. This is especially true if blood pressure is not well controlled when pregnancy begins.
High blood pressure that develops during pregnancy can be a sign of complications such as preeclampsia.
In order to make your pregnancy as safe as possible (for you and your baby):
- See a doctor for regular prenatal care.
- Avoid smoking and alcohol; they both make complications of high blood pressure worse.
- Manage your blood pressure before pregnancy through diet and exercise.
- Continue good eating habits during pregnancy, including a low-salt diet.
- Don’t attempt to lose weight during pregnancy, even if you are overweight.
- Ask your doctor if you should avoid exercise during pregnancy if you have high blood pressure. Your doctor may recommend that you avoid vigorous exercise during pregnancy. (Exercising during pregnancy might lead to less blood flow through the placenta.)
- Discuss your need for blood-pressure medication with your doctor before and during pregnancy, and make sure any medicine you take during pregnancy is safe.
Blood Pressure Medicines During Pregnancy
|Methyldopa||Doctors have prescribed methyldopa for years to treat high blood pressure in pregnancy. Recently, however, as other medications have been judged more effective, it has been used less often. Studies have found no decrease in placental blood flow and no problems in children as old as 7.5 years who were exposed to the drug in the womb.|
|Labetalol||Labetalol has both alpha and beta blocking properties. The drug dilates blood vessels more than drugs that are only beta-blockers. Widely used, it has not been associated with any bad effects on the pregnancy.|
|Beta-blockers||Beta-blockers such as atenolol and metoprolol appear to be safe for use during pregnancy. Although some studies have associated the use of beta blockers with fetal growth problems, it remains unclear if the growth problems are a result of the medication or a result of the high blood pressure itself. For many women, the balance of risks and benefits favors using beta blockers.|
|Use Caution in Some Situations|
|Calcium channel blockers||Calcium channel blockers are used in pregnancy, and research indicates they are usually safe, especially when used later in the pregnancy. Mixing them with magnesium sulfate (a drug commonly used to treat preterm labor) can lead to a rapid and excessive blood-pressure decrease.|
|Diuretics||Diuretics can be considered, with close prenatal care, if the woman had been taking it regularly prior to pregnancy. Because diuretics work by decreasing the amount of fluid in the body’s blood vessels and because fluid volume is already a problem when women have preeclampsia, diuretics should be used very cautiously if the pregnancy is thought to be complicated by preeclampsia.|
|Hydralazine||Hydralazine and labetalol are the two medicines used most commonly to treat severe high blood pressure that must be lowered immediately. Each can be given intravenously.|
|ACE inhibitors||These medicines can cause poor fetal growth, a reduced amount of amniotic fluid, kidney failure in the baby and neonatal death. Many of these problems develop when ACE inhibitors are used late in pregnancy. ACE inhibitors are usually stopped as soon as pregnancy is diagnosed.|
|Angiotensin II receptor blockers||Though no adverse effects have been proven, it is suspected that these medications would cause the same problems as ACE inhibitors.|
Blood Pressure Medicines And Breast-Feeding
All blood-pressure medicines that have been studied for use during breast-feeding do enter the breast milk. Most are thought to be safe to use while breast-feeding. Always tell your pediatrician what medications you are taking. Very rarely, the amount of medicine in your breast milk will be enough to affect a baby and its blood pressure. In general, however, the positive effects of breast feeding and the positive effects of the medicine on your health outweigh the risks associated with breastfeeding while taking medication for blood pressure.
Damage from High Blood Pressure
High blood pressure seldom produces symptoms, but the intense pounding of blood gradually damages your arteries, which then interferes with normal circulation.
Artery damage interferes with normal circulation in two ways:
- Wall thickening occurs because arteries respond to high blood pressure by thickening their muscle layers. This muscle thickening does not make arteries stronger. Instead, when arteries become thick, they lose their elasticity, making them more fragile and prone to rupture. Thickening also narrows the passageway, making it harder for blood to flow. Small arteries are especially at risk.
- Atherosclerosis is the buildup of cholesterol (often called “plaque”) and scar tissue within the artery walls. This tends to happen in areas with the most turbulent blood flow. Areas where arteries divide or bend can have the most sizable plaque deposits. These deposits narrow the passageway for blood flow. Deposits can also develop cracks that trigger a blood clot to form. A blood clot can create a sudden blockage in the artery, cutting off oxygen. This can result in a heart attack or stroke.
High blood pressure eventually damages the organs that rely most heavily on continuous and efficient blood flow — the heart, brain, kidneys, eyes and blood vessels. These are the “target organs” of high blood pressure.