May 21, 2019

What is preeclampsia and how widespread is it?

By Dr. Amanda Henry, The George Institute

Preeclampsia is a pregnancy-related condition characterised by high blood pressure and evidence of other effects on organs of the pregnant woman and her baby, such as protein in the urine, abnormal blood tests results, and a smaller than expected baby.

The condition is most commonly experienced during the second half of pregnancy or soon after the baby is delivered but its symptoms (that include headache, visual disturbance, upper abdominal pain, and chest pain) are only displayed in half of women affected, and as such blood pressure monitoring throughout pregnancy is vital.

Women diagnosed with preeclampsia are at a much greater risk of developing life-threatening complications during pregnancy, including kidney failure, liver impairment, and seizures. Worldwide, preeclampsia is in the top three direct causes of maternal death and severe illness, with 99% of the approximately 40,000 annual preeclampsia-related deaths occurring in low-to-middle-income countries. It’s also a leading cause of stillbirth, newborn death and preterm birth.

Cause and predisposing factors

Despite its long history, the direct cause of preeclampsia remains unclear. Women whose mothers themselves had preeclampsia are at twice the risk, suggesting genetic predisposition. Problems with the normal “immune tolerance” of pregnancy, which allows a mother to carry a baby to term that is genetically different to her, are also important: first-time mothers and assisted conception/IVF pregnancies are also at higher risk. Several preeclampsia risk factors also overlap with heart disease and stroke risk, such as obesity, diabetes, and pre-pregnancy hypertension. Women diagnosed with preeclampsia have at least a doubled long-term risk of heart disease and stroke compared to women with an uncomplicated pregnancy. This is unlikely to be a coincidence, with the demands of pregnancy “unmasking” a woman’s future predisposition to health issues later in life.

Treatment and cure

Medication can be used to control blood pressure, at least for a time, but the underlying disease remains, and the risk of poor pregnancy outcomes continue to increase, sometimes over a very short time. This means the only ‘cure’ is to give birth, sometimes long before the due date. No medications can safely halt established preeclampsia, although several are being trialled. So what to do in future?

Lastly, recognition that preeclampsia is not just disease of pregnancy: it has long-term associations with maternal and child health problems, including a doubled risk of two of the biggest killers of women globally; heart disease and stroke. Our team is actively answering the question of “what is normal?” for blood pressure and other physical measurements in the early years after birth, and how this differs in women who have had preeclampsia. Using this data, we and others are also trialing different methods of follow-up and strategies to encourage a healthy lifestyle to reduce women’s long-term health risks.