Your body goes through many changes while you're pregnant, some of them less welcome than others. For unknown reasons, a woman's blood pressure can climb during the second half of her pregnancy.
If your systolic pressure (the upper number) is at or gets higher than 140 or your diastolic pressure (the lower number) is at or gets higher than 90, you have high blood pressure. If so, you may develop preeclampsia, a condition characterized by elevated blood pressure. It's important to note that you may develop preeclampsia even when your blood pressure is not this high. What seems to be important is that your blood pressure goes up significantly over what's normal for you.
During pregnancy, high blood pressure is sometimes accompanied by protein in the urine. A trace amount of protein may be normal, but if there is more than just a little, the doctor will probably want to give you a 24-hour urine test to determine how much you have.
High blood pressure and preeclampsia aren't just nuisances -- they can be serious threats to a pregnancy. As your pressure climbs higher and higher, the blood vessels throughout your body -- including those in the umbilical cord and placenta -- start to narrow. As those vessels squeeze tighter and tighter, your baby may not be able to get all of the oxygen and nutrients he needs to grow.
If you develop high blood pressure before your baby reaches full-term, you may be more likely to go into labor early, and your baby could be born underweight. High blood pressure during pregnancy can also make you vulnerable to placental abruption, a very serious complication where the placenta breaks free from the uterus before delivery. In some cases, untreated preeclampsia can turn into eclampsia, a condition that causes seizures and, less frequently, coma.
Any pregnant woman can suddenly develop high blood pressure or preeclampsia, but these problems are especially common in teenagers, women over 40, women who are carrying multiple babies, and women who already had high blood pressure before they got pregnant. Other risk factors include a family history of preeclampsia, preeclampsia in a previous pregnancy, kidney disease, diabetes, and obesity.
Now you know why just about every health care provider who gets within five feet of you wants to check your blood pressure and urine. But as important as these pressure checks are, they can't take the place of old-fashioned vigilance. Although high blood pressure is often called a "silent" disease because most people don't notice any symptoms, preeclampsia often comes with telltale warning signs. People with preeclampsia may have other problems that can be detected in blood tests, so doctors often order these tests when they suspect you have the condition.
As your pregnancy progresses, watch out for the following symptoms:
- Rapid weight gain. Again, weight gain during pregnancy is hardly surprising. But if you're gaining more than five pounds in a week, schedule an appointment with your doctor. It's possible that you may be developing preeclampsia.
- Severe headaches
- Small urine output
- Blood in your urine
- Vomiting blood
- Extreme nausea or vomiting
- Ringing in the ears
- Blurred vision, double vision, or flashing lights in your eyes
- Stomach pain
Whether you have preeclampsia or just run-of-the-mill high blood pressure, you'll need extra care throughout your pregnancy. Your doctor may prescribe blood pressure medications or bed rest to keep your pressure down. If your pressure is still climbing too high, your doctor may recommend inducing labor or delivering through a cesarean section as soon as your baby is ready.
Your blood pressure will drop after childbirth, if it's pregnancy-induced hypertension. And because you have high blood pressure in one pregnancy, it doesn't mean you will have it with all of your other pregnancies. Hopefully, the rise in blood pressure is only temporary.
American Academy of Family Physicians. High Blood Pressure During Pregnancy. http://www.familydoctor.org/695.xml
March of Dimes. High blood pressure during pregnancy. http://www.marchofdimes.com/professionals/681_1222.asp
Preeclampsia Foundation. Signs and Symptoms. http://www.preeclampsia.org/symptoms.asp
American Academy of Family Physicians. Preeclampsia. http://www.familydoctor.org/064.xml
National Heart, Lung, and Blood Institute. High blood pressure during pregnancy. http://www.nhlbi.nih.gov/health/public/heart/hbp/hbp_preg.htm
Merck Manual. Risk Factors That Develop During Pregnancy. http://www.merck.com/mmhe/sec22/ch258/ch258c.html
Surbek D.V. et al. Effect of preeclampsia on umbilical cord blood hematopoietic progenitor-stem cells. American Journal of Obstetrics and Gynecology. 185(3) http://www.ncbi.nlm.nih.gov/
National Heart, Lung, and Blood Institute. What Are High Blood Pressure and Prehypertension? http://www.nhlbi.nih.gov/hbp/hbp/whathbp.htm
Mayo Clinic. Preeclampsia: Risk Factors. http://www.mayoclinic.com/health/preeclampsia/