Blood pressure is a measure of the pressure in the vessels that carry blood through the body. If blood pressure is too high, risks to both the mother and baby may occur. This high blood pressure, or “hypertension,” may cause the baby to not receive adequate nutrients or adequate oxygen to grow properly.
For these reasons, blood pressure is taken each time a pregnant woman is seen in a doctor’s office. If the blood pressure is too high, it may be rechecked. An example of a blood pressure is: 120/85. The “top” number is called the systolic pressure. The second number, or the “bottom” number, is termed the diastolic pressure. Both numbers are important. Because a person’s blood pressure may change, depending on the time of day or activity, a single blood pressure measurement may not be sufficient to make a decision on what should be done.
Types of High Blood Pressure in Pregnancy
- Chronic hypertension – In some cases, a woman may have high blood pressure even before pregnancy starts. This is likely to remain throughout the course of the pregnancy and still be present after the birth of the baby. If the patient had been taking medication for high blood pressure before the pregnancy, she will usually continue this during the pregnancy. Some types of high blood pressure medication should not be taken during pregnancy, and the doctor will determine whether or not a change is necessary.
- Pregnancy-induced Hypertension (PIH) – If high blood pressure is not present before pregnancy, but comes on during the pregnancy, it is termed pregnancy-induced hypertension. It usually happens after the fifth month of pregnancy, and it is expected to go away after the baby is born.
Other terms that are used to describe high blood pressure in pregnancy include “pre-eclampsia” and “toxemia.”
Signs of PIH
Sometimes, the patient does not realize that she has high blood pressure, but other symptoms may suggest that her blood pressure is elevated. These include:
- Blurred vision
- Spots in front of the eyes
- Swelling of the hands and feet
- Constant or severe headaches
- Sudden, excessive weight gain (more than one pound per day)
- Pain in the upper right portion of the abdomen
Treatment of High Blood Pressure in Pregnancy
If medications have been taken for high blood pressure, the patient should let the doctor know and continue them if instructed to do so. There is no known way to prevent PIH, so the mother and the baby are best served by seeing her physician on a regular basis and following instructions of the physician when high blood pressure is detected. The only sure cure for PIH is delivering the fetus. This will be done when considerations for the mother and the fetus are weighed together. This may require induction of labor, or it may require that a cesarean birth be performed. In some cases, attempts may be made to prolong the pregnancy to allow the fetus to mature when prematurity is a consideration.
If a rise in blood pressure is detected several weeks before the baby is born, several tests may be done to see if the fetus is developing normally. Ultrasound, for example, will show if the size of the fetus is normal for the number of weeks of pregnancy. It can also detect the presence of too little amniotic fluid, thus showing that the changes in blood pressure have interfered with the growth and the function of the placenta.
Electronic fetal monitoring can measure the fetal heart rate. If the heart rate increases when the fetus moves, this is a sign that the fetus is getting enough oxygen. A drop in the heart rate after a uterine contraction may mean that the fetus is not getting enough oxygen.
If these tests or others show that the fetus is having problems in the uterus, the baby may be delivered as soon as possible. A premature baby will be transferred to an intensive care unit where the baby will be given special care until he or she has gained weight and strength.
In all instances of PIH, the condition of both the mother and the fetus must be considered in order to reach a decision about what will best serve both of them. The patient who has been given as much information as possible will then be better able to make a decision as to what treatments to consider.