High blood pressure (hypertensive) disorders of pregnancy affect 5% - 8% of all pregnancies in the United States. These disorders contribute significantly to serious complications for both the fetus and the mother. Among these disorders is preeclampsia.Preeclampsia is the most common hypertensive (high blood pressure) disorder during pregnancy, affecting an estimated 5-8% of pregnant women each year in the United States, and has the greatest effect on maternal and infant outcome. Over the past decade, the rate of preeclampsia has increased by nearly one-third.Preeclampsia is a condition that typically starts after the 20th week of pregnancy and is marked by increased blood pressure and protein in the mother's urine (as a result of kidney problems). Preeclampsia affects the placenta, and it can affect the mother's kidney, liver, eyes (retina), and brain. Preeclampsia is also a leading cause of fetal complications, which include low birth weight, premature birth, and stillbirth.There is no proven way to prevent preeclampsia. And, there is no proven cause of preeclampsia.Sometimes preeclampsia is called “pregnancy-induced hypertension” or “acute hypertensive disease of pregnancy.”
Eclampsia is a more severe form of preeclampsia that can cause seizures and coma in the mother. When preeclampsia becomes severe and causes seizure activity, the condition is known as eclampsia. An estimated 1 in 200 women who have preeclampsia develop eclampsia.
Eclampsia can be fatal if it's not treated quickly, and is the second leading cause of maternal death in the United States.Difference Between Preeclampsia and Other High Blood Pressure Disorders
An important distinction exists between preeclampsia, recognized when elevated blood pressure occurs for the first time during pregnancy, and preexisting (chronic) hypertension. The two disorders, although both characterized by high blood pressure, are strikingly different pathophysiologically and have very different acute and long-range effects on the health of both mother and baby.A distinction should also be made between high blood pressure of pregnancy and preeclampsia. Many pregnant women develop mild blood pressure, but most of those do not have preeclampsia. About 20% of those women progress to preeclampsia which involves high blood pressure and abnormal protein in the urine.
Preeclampsia Risk FactorsThe cause of preeclampsia is unknown. There are certain characteristics that appear to be risk factors for a woman to develop preeclampsia during pregnancy. Studies have identified any or all of the following as preeclampsia risk factors:--First pregnancy at age over 35; -- A multiple pregnancy (women who are pregnant with more than one baby); -- Preexisting diabetes; -- Obesity; -- Women younger than age 20, or older than age 40; -- Preexisting autoimmune conditions; -- Preexisting kidney disease; -- Preeclampsia in a previous pregnancy; -- Preexisting chronic hypertension (women who have high blood pressure before becoming pregnant). In recent years, preexisting chronic hypertension has affected an increasing number of women, and has resulted in a significant risk for the development of preeclampsia during a pregnancy. Preeclampsia occurs more frequently and is more severe in women with preexisting hypertension than in women who do not have high blood pressure before pregnancy.
Preeclampsia Signs and Symptoms
Some pregnant women notice no symptoms of preeclampsia. However, there are some common signs and symptoms that can result from preeclampsia. The severity of preeclampsia is usually related to the blood pressure level. You may have no symptoms at first, or if you have only mildly raised blood pressure and a small amount of leaked protein in your urine. If preeclampsia becomes worse, one or more of the following symptoms may develop. With any of these, you should notify your doctor and go in for an office visit:-- Excessive swelling in the hands and face ((a woman’s feet might swell too, but swollen feet are common during pregnancy and may not signal a problem);-- Persistent headaches;-- Belly or abdominal pain (Pregnant women with suspected gallstones should also be evaluated and tested for preeclampsia because belly pain from gallstones is often felt in the same place as belly pain from preeclampsia);-- Blurry vision and/or sensitivity to light;However, these symptoms are not necessarily due to preeclampsia. They can occur even if the pregnant woman does not have preeclampsia, and they can be caused by other disorders. They can even occur in healthy pregnancies.One specific subset of signs and symptoms is known as the HELLP Syndrome (Hemolysis, Elevated Liver Enzymes, and Low Platelets). This combination of signs and symptoms signals a serious and complicated case of preeclampsia which can result in severe illness and even death. Prenatal care is important. Regular doctor visits are needed to monitor and diagnose any symptoms, track the mother’s blood pressure and level of protein in her urine, order and analyze blood tests that detect signs of preeclampsia, and monitor fetal development.Preeclampsia Screening and Testing
There is no single test to predict or diagnose preeclampsia. It is a condition characterized by high blood pressure and protein in the urine. Generally, preeclampsia should be considered when any blood pressure in pregnancy is 140/90 or higher (a normal blood pressure in pregnancy is 120/80 or less). Screening for preeclampsia is the reason blood pressure is frequently checked at prenatal visits. The diagnosis is confirmed when the blood pressure is elevated and excessive protein is found in the urine. If pre-eclampsia is suspected it is also important to do blood work to check the mother’s liver and the ability of the mother’s blood to clot. An ultrasound to evaluate fetal growth should be done, as well as close monitoring of the baby for signs of impaired oxygen.
Blood Pressure Levels in Preeclampsia
Normal blood pressure is below 140/90 mmHg. The first number (systolic pressure) is the pressure at the height of the contraction of the heart. The second number (diastolic pressure) is the pressure in the arteries when the heart rests between each heart beat.• Mildly high blood pressure is 140/90 mmHg or above, but below 160/100 mmHg.
• Moderate to severe high blood pressure is 160/100 mmHg or above.
High blood pressure can be just a high systolic pressure, for example, 170/70 mmHg, or just a high diastolic pressure, for example, 130/104 mmHg . Or both, for example, 170/110 mmHg.
However, any substantial rise in the blood pressure from a reading taken in early pregnancy is a concern, even if it does not get as high as the levels listed above. If you have low blood pressure before pregnancy, the relative amount of change is important, not just the actual levels.
Most women have mild preeclampsia and will be managed with bed rest and close monitoring. The chance of getting to full term delivery is very good if the disease does not become severe. The only way to "cure" preeclampsia is to deliver the baby. Severe cases of preeclampsia where the mother or baby are seriously compromised or at risk do require delivery of the baby, even if the baby is preterm. This is because if left untreated in these cases, the condition can be fatal for the mother and/or her baby, or can lead to long-term health problems. Severe preeclampsia is diagnosed when the blood work is abnormal, the blood pressure is excessively high, or the baby is not getting enough oxygen.
Effects on Mother’s Health
In the United States, hypertensive disorders of pregnancy account for nearly 15 percent of maternal deaths; throughout the world these conditions are responsible for more than a third of maternal deaths. Possible complications for the mother’s health include edema, thrombotic disorders and renal failure. Preeclampsia also can develop into eclampsia which can result in the mother having a stroke or seizures, and can be fatal.There may also be long term consequences to the mother’s health. Women with chronic hypertension have an obvious long-term risk from the persistent hypertension. However, women with preeclampsia, despite the resolution of the disorder after delivery, are also at increased risk of cardiovascular disease in later life compared to women with pregnancies without preeclampsia. However, studies have also shown that in uncomplicated cases of preeclampsia, women are not at higher risk of developing chronic high blood pressure (hypertension) after delivery.Effects on Fetus Before Birth, or Baby After Delivery
Fetal complications of preeclampsia (and also other hypertensive disorders of pregnancy) include fetal growth restriction, IUGR, prematurity, and stillbirth.This illustration shows how preeclampsia can restrict the perfusion of the mother’s blood vessels into the placenta and disrupt the exchange of oxygen, nutrients, and waste products between the mother and the placenta. In normal placental development, the maternal spiral arteries are transformed into high caliber vessels capable of sustaining the growing fetus. In preeclampsia, the mother’s spiral arteries can remain small and low capacity insufficient to sustain normal fetal growth (lower panel).The long-term effects of preeclampsia on the baby are more difficult to predict. Depending on how severe the preeclampsia is, there may be increased risks that the baby will suffer fetal distress and/or slowed growth disorders. There is also evidence that preeclampsia is associated with an increased risk that the baby will suffer cardiovascular disease as an adult. This association may be related to the intrauterine milieu in a hypertensive pregnancy and the failure of the fetus to exercise full growth potential.