How a Woman's Blood Pressure Responds to Pregnancy
Blood pressure isn't the same during a pregnancy as before the pregnancy. The pregnant woman's body goes through many changes to provide the best possible environment for the growing fetus. The mother-to-be must sustain the placenta, the umbilical cord (the connection between the mother and the fetus), and the fetus itself with nutrition and fluid. To do this, the expectant mother's blood vessels widen, and the volume of water and salt increases in her body. She gains about 8 liters (2 gallons) of water.
The opening of blood vessels normally causes the blood pressure to fall during the first six months of the pregnancy. (A woman with pre-existing high blood pressure may even be able to stop high blood pressure medications during pregnancy because the blood pressure may drop into the normal range.)
Pre-existing conditions, especially those related to high blood pressure, are extremely important to control during a pregnancy. Work with your doctor if
- You suffer from kidney disease. The risk of kidney failure increases significantly during pregnancy. Potential mothers should discuss with their doctor whether pregnancy is advisable.
- For this reason, be sure to get a complete medical evaluation prior to becoming pregnant for any evidence of target-organ damage (damage to the organs that high blood pressure affects, especially in the heart, kidneys, and eyes).
- You're on ACE inhibitors or angiotensin receptor blockers. These must be stopped because they may damage the fetus. Other classes may be used prior to becoming pregnant.
- You have high blood pressure before you become pregnant. Have your doctor check your blood pressure after you become pregnant to see whether you can reduce or stop blood pressure medication.
- You have high blood pressure before your pregnancy and are able to stop your medications for the first six months. Consider staying off the medications for the rest of the pregnancy, even if your blood pressure rises — so long as you have no eye, kidney, or heart damage. Note: You may be able to stay off the meds as you breast-feed as well.