Preeclampsia is a disease that only happens during pregnancy. Learn how it's diagnosed and what experts have to say when it comes to prevention.

pregnant woman at doctor
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Preeclampsia during pregnancy is a disease defined by the presence of two symptoms beginning after your 20th week: (1) elevated blood pressure and, (2) proteinuria (the presence of protein in your urine). 

More specifically, preeclampsia is a blood pressure of 140 over 90 on two occasions separated by at least six hours in the second half of pregnancy in a woman who has not previously had high blood pressure, according to John Repke, M.D., chairman of the department of obstetrics and gynecology at Penn State Hershey College of Medicine in Hershey, PA. "The second component of it is 300 milligrams or more of protein in the urine in a 24-hour collected specimen."

Your health-care provider will monitor you for preeclampsia by checking your blood pressure and testing your urine. Therefore, your weekly visits at the end of pregnancy are especially designed to try to catch this disease early.

In recent years, some researchers have suggested a name change for the condition. Co-author of an editorial in the journal Anaesthesia cited in Science Daily, associate professor Alicia Dennis, who is consultant anaesthetist and director of anaesthesia research at the Royal Women's Hospital in Melbourne, Australia, says the condition may be a result of problems getting adequate oxygen to the developing fetus. So she suggests changing the name of the condition to hypertension caused by pregnancy might help women better understand it, and get the info they need to manage it.

"Referring to it as hypertension caused by pregnancy, rather than the historically outdated name of preeclampsia, would mean that women worldwide could be better informed and counseled about the condition," she wrote, as cited in Science Day.

Preeclampsia Causes

The jury's still out on what exactly causes preeclampsia. "The most accepted explanation is a problem with the placenta, which produces substances that cause the clinical condition that we call preeclampsia," says Maurice Druzin, M.D., professor of obstetrics, gynecology, and maternal fetal medicine at Lucile Packard Children's Hospital Stanford, in Palo Alto,CA.

Another theory is that an imbalance in prostaglandins – substances that help relax and contract smooth muscles during pregnancy – causes blood vessels to constrict, says Virginia R. Lupo, M.D., chair of the department of obstetrics and gynecology at Hennepin County Medical Center in Minneapolis. While a 2014 study suggests that the condition may be brought on by insufficient oxygen to the fetus.

What experts do know is that preeclampsia is characterized by vasospasm (abnormal constriction of blood vessels). It is more common with first-time pregnancies, as well as in women who are carrying multiples, are over 40, are obese, or have a personal or family history of the condition, according to the Mayo Clinic.

Your genetic makeup may also play a role. "We think that preeclampsia actually is a marker for a patient whose vasculature, or arrangement of blood vessels, is pre-destined to have some abnormality," explains Dr. Druzin.

How to Prevent Preeclampsia

Because doctors are not sure why the condition develops, it's difficult to prevent it. Small research trials have shown limited success with low-dose aspirin or calcium supplements, but larger studies have not confirmed those findings and the practice is not standard.

"The best you can do is get good prenatal care so that preeclampsia can be detected early if you develop it," Dr. Lupo says.

Many women who had preeclampsia with their first pregnancy ask if there are ways to prevent getting it again in the future. Unfortunately, having had preeclampsia in one pregnancy, certainly is a risk factor for developing it again in any subsequent pregnancy.  Often times, this cannot be prevented.

There are, however, certain risk factors that can be addressed to help decrease your risk. Modifiable risk factors for developing preeclampsia include obesity, gestational diabetes (which is also seen more frequently in overweight women) and preexisting high blood pressure. So starting your next pregnancy at your ideal body weight is an excellent first step to help prevent preeclampsia from occurring in your next pregnancy.

"Your best bet is to see a high-risk ob-gyn doctor for a consultation prior to getting pregnant again," advises Elizabeth Pryor, MD, FACOG. "It would be helpful to bring your medical records from your previous pregnancy so the doctor can review the specifics of your case."