Preeclampsia 101

May 16, 2023

May is Preeclampsia Awareness Month. Preeclampsia can strike any time. Keep yourself and your loved ones aware of these most frequently asked questions about this often life-threatening pregnancy disorder.

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What is preeclampsia?

Preeclampsia is a pregnancy-specific disorder that can impact every organ in a mother’s body. It is often signified by new onset high blood pressure, specifically a blood pressure greater than 140/90. Preeclampsia can also be characterized by proteinuria, or the presence of protein in the urine.

The organs most commonly impacted by preeclampsia are a woman’s kidney, liver, platelets and brain. In addition, this disorder may also restrict the baby’s growth and can cause a higher risk for stillbirth.

What causes preeclampsia?

While the exact cause of preeclampsia remains unknown, there are several theories as to what causes this disorder. One theory is that it may be caused by abnormal placental implantations and development. Simply put, during initial implantation of the pregnancy, the developing placental blood vessels do not undergo the necessary changes to allow them to adapt to the growing pregnancy.  As a result, they are stiffer and smaller in diameter than normal placental blood vessels.  This causes suboptimal blood flow and oxygen delivery to the placenta and the release of inflammatory substances into the maternal blood stream causing the clinical syndrome of pre-eclampsia.

A second theory is it is a result of immunologic intolerance to paternal and fetal antigens. In broader terms, this means that there is an abnormal maternal immune response to the developing placenta and fetal tissue.

Doctors also believe this disorder may be caused by endothelial cell damage and inflammation. What this means is that pro-inflammatory substances cause damage to endothelial cells, the cells that compose blood vessels.  Once damaged, these cells leak fluid into the surrounding tissues, produce an abnormal amount of vasodilatory hormones and activate platelet clumping which occludes small blood vessels and impair blood flow and oxygen delivery to body organs.

A final theory is that preeclampsia is brought on by different genetic factors that are carried by either the mother or the father.

What are the symptoms of preeclampsia, and when does it occur in pregnancy?

Women suffering from preeclampsia will experience new onset high blood pressure greater than 140/90, with or without protein in the urine. Other symptoms may include:

Preeclampsia is classified as either mild or severe based on the degree of multi-organ involvement and a patient’s symptoms. Preeclampsia is a progressive disorder, so mild cases will eventually develop into severe preeclampsia if not treated.

In addition, women with chronic high blood pressure may be diagnosed with superimposed preeclampsia. This is most typically seen in women with hypertension associated with diabetes, preexisting autoimmune disorders and chronic kidney disease.

While the majority of preeclampsia disorders are diagnosed after 34 weeks gestation and within 48 hours of delivery, it may be seen as early as 20 weeks gestation and up to six weeks post-delivery.


Who is at the highest risk for developing preeclampsia?

Risk factors for preeclampsia include a wide variety of factors, such as:

  • First time mothers or pregnancy with a new partner
  • Young mothers
  • Black women
  • Medical problems including chronic hypertension, kidney disease, lupus, diabetes and heart disease
  • Pregnancies with multiples
  • Molar pregnancy
  • Obesity
  • History of preeclampsia in prior pregnancies
  • IVF pregnancies – particularly those with donor eggs

In addition to the risk factors above, mothers with pregnancies spaced too closely together or very far apart can be at risk. Too close may be defined as 18 months or less and far apart as 4-5 years between pregnancies.

How does preeclampsia affect pregnancy?

Preeclampsia can be very dangerous to both the mother and the baby. The very high blood pressure can result in seizures, stroke, liver and renal dysfunction, bleeding abnormalities, placental abruption, hemorrhage, and even death if left untreated.

If a mother-to-be suspects she may be experiencing preeclampsia, she should contact her doctor immediately.

How is preeclampsia treated?

Today the only cure for preeclampsia is delivery. If a mother is diagnosed with severe preeclampsia, magnesium sulfate will be given immediately through an IV to prevent seizures. The dangerous high blood pressure may also be treated with anti-hypertensive medications.

If a pregnant woman has preexisting risk factors, she should talk to her doctor about possible preventative measures that may lower the risks.


How does preeclampsia impact the baby?

This dangerous disorder can cause the baby’s growth to be restricted and increases the risk of stillbirth. In the most severe cases, preterm delivery may be required which may then expose the baby to the complications of prematurity such as under-developed organs, breathing difficulties, jaundice, anemia, a lowered immune system, etc.

In the worst cases, fetal death can occur from a sudden detachment of the placenta from the uterus.

For these reasons, women diagnosed with preeclampsia undergo additional monitoring such as: ultrasounds every 4 weeks to evaluate fetal growth, lab work to determine if there is multi-organ involvement, etc. and delivery no later than 37 weeks.

If you are worried you are at risk of developing this dangerous disorder, please be sure to consult with your doctor and discuss your concerns immediately.

About the authors

preeclampsia, prematurity, aagaard, texas children's, preeclampsia, texas children's hospital, dr rac, pregnancy, prematurityCo-authored by Dr. Martha Rac and Dr. Kjersti Aagaard. Both Dr. Rac and Dr. Aagaard are maternal-fetal medicine experts at Texas Children’s Pavilion for Women. In their roles at Texas Children’s they work to help both moms and babies have the healthiest life, both during and after pregnancy.