Hypertension is a condition that develops when you’re blood pressure is too high. Pregnant women who have hypertension are at a higher risk of stroke and complications during delivery. One disorder that causes high blood pressure during pregnancy is called preeclampsia.

Experts aren’t sure what causes this condition. Preeclampsia can damage your organs and be very dangerous to your baby if it isn’t treated. Besides high blood pressure, preeclampsia can also cause:

  • excess protein in your urine, which is a sign of kidney problems
  • headaches
  • changes in vision
  • upper abdominal pain
  • decreased urine output

Your doctor should monitor your blood pressure frequently throughout your pregnancy. If you develop preeclampsia, your doctor may prescribe antihypertensive medicines. This will regulate your blood pressure and prevent complications.

Several medications are available for pregnant women with high blood pressure due to preeclampsia. These include:

Methyldopa

Methyldopa has been studied extensively and is recommended by many experts as the first-line oral antihypertensive medication in pregnancy. It’s a centrally acting, alpha-adrenergic agonist. This means that it affects the central nervous system and stops the brain from sending signals for the blood vessels to constrict, which would raise blood pressure.

This is referred to as vasoconstriction. Methyldopa can be given in pill form or intravenously in severe cases.

Labetalol

Labetalol another first-line oral antihypertensive medication that blocks blood vessel receptors, which cause vasoconstriction. Labetalol is prescribed in pill form or is given intravenously.

Nifedipine 

Nifedipine is a calcium channel blocker. It works by relaxing blood vessels and reducing the heart rate. This drug isn’t used as extensively as methyldopa and labetalol. When used during pregnancy, a long-acting formula like Procardia XL or Adalat CC is preferred. This is because the short-acting formula puts mother and baby at risk for sudden and severe drops in blood pressure, or hypotension.

Your doctor won’t prescribe nifedipine if you’re receiving magnesium sulfate therapy. The combination of these drugs may cause excessively low blood pressure and may have negative effects on your muscle and nerves. When taking this medication, you shouldn’t allow it to dissolve under your tongue. This can cause blood pressure levels to fluctuate unpredictably.

Hydralazine 

Hydralazine is another drug that can be given orally or intravenously to control hypertension in pregnancy. This drug may be used as an injection in very severe cases of high blood pressure. It relaxes your blood vessels, which increases the amount of oxygen and blood that goes to your heart. This allows your heart to do less work.

Atenolol clonidine are other possible options. However, pregnant women don’t use them as extensively as the medications listed above.

Medicines to avoid during pregnancy

There are some blood pressure medications that you should avoid during your pregnancy. These include:

Angiotensin converting enzyme inhibitors

Angiotensin converting enzyme inhibitors interfere with the body's production of a chemical that causes the arteries to constrict. Using these drugs during pregnancy is associated with birth defects such as:

  • fetal hypocalvaria, or a small fetal head
  • renal defects
  • anuria, or absence of urine
  • fetal and neonatal death

Diuretics

Diuretics such as furosemide (Lasix) and hydrochlorothiazide (Microzide) should be avoided during pregnancy. These lower blood pressure by clearing extra fluid and salt from the body and dilating blood vessels.

Propranolol

Propranolol is a beta-blocker that lowers blood pressure by reducing heart rate and the amount of blood pumped by the heart. It has been associated with birth defects, such as fetal bradycardia, or slow heartbeat, slowed development, and neonatal hypoglycemia.

Controlling high blood pressure is an important part of the treatment for preeclampsia. Medications can help you treat it, but the only way to cure the disorder if you’re pregnant is to deliver your baby. Depending on the severity of your symptoms and how near to term you are, your doctor may decide that it’s necessary to deliver your baby right away.