Blood pressure disorders are the most common medical complication experienced during pregnancy, occurring in approximately 5-10% pregnancies. The most common blood pressure disorder, preeclampsia, is unique to pregnancy, and although the primary finding is high blood pressure, it can also be associated with other signs of damage to various organ systems. Damage to the kidneys is most commonly seen, and usually results in excess amounts of protein in the urine. As the disease process progresses, however, compromise to the liver, brain, and vascular system can also occur. This damage to the organs occurs because preeclampsia causes blood vessels to constrict and spasm, which not only leads to elevated blood pressure, but also decreased blood flow to these vital organs.
Preeclampsia is usually diagnosed after 20 weeks of gestation, but most often will develop after 37 weeks of gestation. Your obstetrician will check for signs of preeclampsia at each prenatal visit by checking blood pressure and assessing the urine for protein; these assessments increase with more frequent prenatal visits towards the end of pregnancy. Your obstetrician will also screen for symptoms of preeclampsia such as headache, visual changes, mid-abdominal or right upper abdominal pain, or any new-onset nausea and vomiting. Swelling in the face, hands, or extremities can also be seen with preeclampsia, but can also occur in patients with completely normal pregnancies.
Not only can signs and symptoms of preeclampsia occur in the mother, but certain signs may also present with the developing baby. In some cases, the baby may not be growing well in the uterus or the amniotic fluid volume may be low. If any of these issues arise during the pregnancy, both mom and baby will be very carefully monitored. Fortunately, in most cases, the baby is not affected.
The exact cause of preeclampsia is unknown. Many theories have been suggested and explored, but no definitive answer has ever been reached. We do know that certain women have a higher risk of developing preeclampsia than the general pregnant population. Risk factors for preeclampsia include: first pregnancy, obesity, gestational diabetes, multi-fetal gestation (i.e. twins, triplets, etc.), family history of preeclampsia or preeclampsia in a prior pregnancy or poor outcome in a previous pregnancy such as placental abruption or fetal death. Extremes of age are also an important risk factor; women <20 and >35 have a higher risk of developing the preeclampsia. Finally, women with certain pre-existing medical or genetic conditions are at higher risk. This includes women with chronic hypertension, kidney disease, Type 1 diabetes, or blood clotting disorders.
Another potential risk factor has come into play in the recent years with advances in assisted reproductive technology (ART), such as the increased use of intrauterine insemination (IUI) and in vitro fertilization (IVF). Women aged 35 years and older have a higher risk of encountering difficulties conceiving and are more frequently turning to ART to achieve pregnancy. These techniques can challenge the immune system of the mother, which may put her at a higher risk for developing preeclampsia. In addition, many women undergoing ART also become pregnant with twins or triplets. The combination of ART and multi-fetal gestation further increases the likelihood of developing preeclampsia.
Preeclampsia is typically diagnosed by obtaining elevated blood pressure readings of >140/90, at least two times and measured 6 hours apart. Once these blood pressures are reached, other tests will be performed to assist in the diagnosis. Laboratory tests will be done to look at how the liver, kidneys, and vascular system are functioning. If protein is found in the urine or the laboratory values show signs of organ compromise, the diagnosis is confirmed. In addition, if any of the symptoms of preeclampsia such as persistent headache, visual changes, or significant abdominal pain are present, the diagnosis of preeclampsia is also likely and you will be very closely monitored. It is important that the diagnosis of preeclampsia be achieved in a timely fashion, in order to prevent the development of more serious complications such seizures, placental abruption, or bleeding in the brain.
The definitive treatment for preeclampsia is delivery of the baby. Luckily, most cases of preeclampsia are diagnosed near the end of pregnancy, which decreases the risks of complications associated with premature delivery of the baby. If preeclampsia develops before 37 weeks of gestation, which is considered preterm, hospitalization and close monitoring for worsening signs or symptoms is usually indicated. Many women who are diagnosed with preeclampsia before 37 weeks and are stable will be monitored until they reach 37 weeks of gestation, at which time delivery will be recommended. Although preeclampsia is more commonly diagnosed late in the third trimester, it is important to keep in mind that it can develop much earlier in pregnancy. As a result, it is important to let your obstetrician know of any signs or symptoms you may be experiencing. If you are diagnosed with preeclampsia early in pregnancy, your doctor will weigh the risks and benefits of keeping you pregnant as long as possible versus delivery of the baby. Finally, preeclampsia can sometimes develop into more severe forms of the disease, i.e. HELLP syndrome and eclampsia. If either of these develops, delivery, regardless of gestational age, is recommended.
The good news for pregnant women is that having a healthy, normal pregnancy is much more likely than developing preeclampsia. With that said, being informed about the disease, knowing your risk factors, and being in-tune to your body is very important. If you have any concerns about symptoms you are having and think they may be related to preeclampsia, do not hesitate to see your obstetrician.
Gabbe, S.G., Simpson, J.L., and Niebyl, J.R. (2007) Obstetrics: Normal and Problem Pregnancies, 5th Edition. Philadelphia, PA: Elsevier Health Sciences, 863-866.