What causes preeclampsia?

Dangerously elevated blood pressure in pregnancy may have a variety of causes.

what causes preeclampsia doctor talks with pregnant patient

High blood pressure in pregnancy is a common medical problem. However, what causes preeclampsia seems to depend on a variety of factors. Preeclampsia — or extraordinarily high blood pressure combined with protein in the urine — affects 5% to 10% of pregnant women.

Because preeclampsia can result in complications for both mother and baby, it is important to consistently monitor prenatal health.

Consult with a specialist: Maternal fetal medicine from Sanford Health

Diagnosis, effects of preeclampsia

Hypertension is the main part of the diagnosis of preeclampsia. It is not fully known what causes preeclampsia but it can affect the patient’s body in a variety of ways. It is known to begin at different gestational stages — and sometimes after the baby is born — and range in severity.

Some patients experience:

  • Swelling in the legs, arms, face or genitals
  • Fluid in the abdomen or lungs

Because preeclampsia can affect any organ in the body, it can cause:

  • Headache
  • Blurred vision
  • Liver failure
  • Kidney failure
  • Platelets, abnormalities in the blood.

Those at higher risk for preeclampsia

Among the risk factors for preeclampsia is being a first-time mom. Two-thirds of all preeclampsia cases occur in women having their first baby. However, there are many other conditions that put patients at increased risk including:

  • Those over age 40
  • In vitro fertilization
  • Family history of preeclampsia
  • Obesity
  • Twins, triplets or other multiples
  • Preeclampsia in a previous pregnancy
  • Chronic hypertension
  • Kidney disease
  • Lupus
  • Diabetes

The risk also increases in women who have limited sperm exposure with the same partner before conception.

A previous normal pregnancy with the same partner is associated with a lower preeclampsia risk. However, the decreased risk is lost with a change of partner or with a prolonged interval between pregnancies.

The role of the father

Studies have shown that the history of the father is an important risk factor for preeclampsia. Men who fathered one preeclamptic pregnancy are nearly twice as likely to father a preeclamptic pregnancy with a different woman. This appears to happen regardless of whether the new partner had a history of preeclampsia.

Causes of preeclampsia

Although specific causes of preeclampsia are unknown, research has developed a variety of theories, including:

  • Abnormal placenta implantation into the uterus early in the pregnancy
  • Abnormal blood vessel development
  • Blood clotting defects
  • Blood vessel damage
  • The mother’s immune system
  • Genetics
  • Overactive inflammation response

Preeclampsia prevention

Previous clinical trials looking for what causes preeclampsia have evaluated:

  • Protein or salt restriction
  • Zinc
  • Magnesium
  • Fish oil
  • Vitamin C or E
  • Calcium
  • Water pills
  • Blood pressure medication
  • Blood thinners

Unfortunately, none of those tests showed a proven benefit in preventing or lowering the risk of preeclampsia.

One method of prevention has been shown to work. Recently, large studies suggested that low dose aspirin (81 mg) can help prevent preeclampsia in patients at risk. Patients with a history of preeclampsia, chronic hypertension, kidney disease, diabetes or multiple gestations can decrease their risk of preeclampsia by taking aspirin in low doses throughout pregnancy. Researchers recommend starting the low-dose aspirin at 12 to 28 weeks gestation.

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Posted In Health Information, Pregnancy, Women's