Updated April 22, 2015.
Preeclampsia is responsible for approximately 20% (about 4 million) of the preterm births each year worldwide. In the United States preeclampsia develops in 6-8% of all pregnancies and its incidence has increased by one third over the last decade. Preeclampsia is one of the leading known causes of prematurity, leading to approximately 109,000 premature births annually.
Preeclampsia is a condition in pregnancy that is defined by its symptoms of increased blood pressure, swelling, and protein in urine that occurs greater than 20 weeks of pregnancy.
Although the cause of preeclampsia is not specifically known, it is thought to be the result of abnormal blood vessels in the placenta. Women with chronic hypertension and certain metabolic diseases like diabetes are more susceptible. Since the placenta is thought to be the cause, the only known way to resolve the condition is through delivery of the baby. Keep in mind that preeclampsia can happen for up to six weeks postpartum as well, so it is important to recognize the signs and get prompt medical treatment if you are showing symptoms of preeclampsia even after your baby is born.
There are two forms of preeclampsia: Preeclampsia-eclampsia (sometimes termed toxemia) and Preeclampsia caused by chronic hypertension. You may also here the terms Pregnancy Induced Hypertension (PIH) or gestational hypertension. Gestational hypertension is blood pressure rising after the 20th week but not accompanied by proteinuria (kidney dysfunction leading to protein in the urine)
Signs of preeclampsia include: persistent headache, swelling, blurred vision, abdominal pain, and an increase in blood pressure.
Blood pressure is the force exerted by the blood against the walls of the arteries. High blood pressure is defined as a reading above 140/90. Preeclampsia can cause the blood pressure to rise and increase the risk of brain injury. It can impair kidney and liver function, and cause blood clotting problems, pulmonary edema (fluid on the lungs), seizures and, in severe or left untreated cases, maternal and infant death. Preeclampsia affects the blood flow to the placenta, often leading to smaller or prematurely born babies.
Mild preeclampsia can be managed with bed rest and careful monitoring of blood pressure and assessing the results of laboratory tests that indicate the condition of the kidney, liver, and how well the blood will clot. Blood pressure medication (antihypertensive) may be used to help keep the blood pressure at a lower controlled level. Hospitalization may be needed allow for close monitoring of signs of instability including very high blood pressure that’s not responding to medication, signs the kidneys are failing (protein in the urine) and blood work that shows a reduced number of red blood cells or platelets. These signs indicate a more severe case of preeclampsia and may need to be managed with an intravenous drug called Magnesium Sulfate (also termed Mag) Magnesium sulfate is used to prevent seizures by blocking or reducing certain areas of the brain. In severe preeclampsia, Magnesium sulfate is ideally given for 24-48 hours while corticosteroids (betamethasone) are administered to help reduce the risk of lung problems of a baby born prematurely.
HELLP syndrome is one of the most severe forms of preeclampsia and occurs in 5-12% of those with preeclampsia. It can lead to injury of the liver, a breakdown of red blood cells and lowered platelet count. HELLP stands for: Hemolysis, Elevated Liver enzymes, and Lowered Platelets.
If preeclampsia cannot be controlled (leading to impending eclampsia and HELLP) delivery of the baby will need to happen as soon as possible as eclampsia is the second leading cause of maternal death in the United States.
Preeclampsia also has some major effects on the growing baby as well and increases the risk of IUGR. (Intrauterine growth restriction) The placenta is responsible for the baby’s survival within the womb as it passes the baby nutrients and oxygen to the baby. Preeclampsia compromises the placenta’s function and the baby’s body begins to restrict blood flow to some of the organs in an effort to preserve the vital blood supply to the brain and heart. The reduced blood flow to the placenta restricts the supply of nourishment to the baby and therefore can lead to a smaller than gestational age baby. Of the 30 million IUGR infants born worldwide each year, 15% (4.5 million) are associated with preeclampsia. In this case IUGR is not associated with the way the mother eats and nourishes herself during pregnancy but rather the placentas function of passing nutrients along to the baby.
Because preeclampsia affects the blood flow to the placenta, it can also lead to abruption. Placental abruption is when the placenta separates from the uterus causing the underlying surface to bleed. As the placenta detaches or dies the baby’s body cannot extract energy from its fuel supply. Without oxygen and blood supply, delivery becomes emergent to save the baby as well as the mother.
Infant death is the most devastating consequences of preeclampsia. In the U.S., approximately 10,500 babies die from the effects of preeclampsia each year and this number is even higher worldwide. Preeclampsia is currently the leading known cause of prematurity. Right now, there is no cure and more research is needed. Early diagnosis through good consistent prenatal care and simple screening measures can predict, manage, and sometimes prevent the adverse outcomes of preeclampsia. Prompt treatment is necessary to save the lives of both mom and baby and will help reduce some of the lifelong challenges that come along with having a baby born prematurely.
To learn more about preeclampsia, please visit The Preeclampsia Foundation website
World Health Organization. "WHO Recomendations for Prevention and Treatment of Pre-eclampsia and Eclampsia." (2011) Accessed April 10, 2012 from http://www.preeclampsia.org/images/pdf/2011c-who_pe_final.pdf
L. K. Wagner, “Diagnosis and management of preeclampsia,” American Family Physician, vol. 70, no. 12, pp. 2317–2324, 2004.
Sibai BM (2003). Diagnosis and management of gestational hypertension and preeclampsia. Obstetrics and Gynecology, 102(1): 191–192.