PREECLAMPSIA has long been the most common, serious medical disorder of pregnancy, affecting 3–5% of pregnancies in Australia.
Although there are no current treatments to reverse or halt established preeclampsia, experts are optimistic. There have been several research findings over the past few years which will work at improving prevention, treatment and long term health of mothers and babies.
New hope from early screening
Dr Fiona Brownfoot, a clinician scientist at the University of Melbourne and a specialist obstetrician, said that to understand the risk factors, it was important to know how preeclampsia occurs.
“We now know that the preeclampsia happens because the placenta releases factors into the mother’s bloodstream that poison the bloodstream. That leads to all of the different maternal organs being involved, such as elevated blood pressure, kidney involvement, liver involvement, and then it can lead to eclampsia (high blood pressure resulting in seizures) and small babies,” she explained.
According to Professor Shaun Brennecke, the Director of the Department of Maternal–Fetal Medicine at the Royal Women’s Hospital Melbourne, the current screening method for preeclampsia is based on the assessment of a woman early in her pregnancy as to whether she has risk factors.
“Risk factors could be a first pregnancy … also women who have pre-existing health problems such as hypertension or kidney disease. As they enter pregnancy, they will be at an increased risk of later on developing preeclampsia, as will women who have a high body mass index and women with multiples or twins,” he explained.
However, there are moves afoot to introduce a new screening practice during the routine 11–13-week ultrasound.
“Looking at the characteristics of the blood flow through the uterine arteries as they feed blood into the placenta at that early stage, you can gain an insight into the likelihood of the woman developing preeclampsia (later in the pregnancy),” Professor Brennecke explained.
This measurement is combined with a blood test measuring the pregnancy-associated plasma protein A (PAPP-A) and placenta-like growth factor (PlGF), a woman’s blood pressure and her medical history. A computer algorithm developed by the Fetal Medicine Foundation in London comes up with a risk score for the likelihood of a woman developing preeclampsia later in the pregnancy.
Currently, this screening is only available at a few centres around Australia, but hopefully this will change soon.
“There is an application to the Medical Services Advisory Committee (MSAC) of the federal Health Department to provide Medicare funding for that test,” Professor Brennecke said.
Decreasing the risk
For women who are at high risk, according to UNSW Sydney Obstetrics and Gynaecology Associate Professor Amanda Henry, there are some promising developments to help them reduce their risk of developing the condition.
“Exercise during pregnancy (moderate intensity of 140 minutes or more each week) decreases the risk of preeclampsia by about 40%,” she advised.
There is good evidence that low dose aspirin can help reduce the risk.
“Low dose aspirin, which is 150 mg of aspirin taken at night from the early part of pregnancy, (in the last few weeks of the first trimester) … or prompted by that ultrasound assessment, you can start at any time before 16 weeks of pregnancy,” said Professor Brennecke.
“There is very good evidence that will reduce the risk of preeclampsia, particularly the preterm or early onset types of preeclampsia, which often carry the most morbidity and mortality for mother and baby.”
Associate Professor Henry said increasing calcium for some women could also help.
“Women who don’t have a diet rich in calcium (calcium-rich being over 900 mg/day, bearing in mind low fat milk is about 250 mg per glass, yoghurt 200 mg persmall tub) should also take calcium supplements to lower their risk. This is estimated to lead to a 50% reduction,” she said.
Awareness of the signs and symptoms
According to Professor Brennecke, it’s important that women are aware of the risk factors and signs and symptoms of preeclampsia.
“There’s an organisation in Australia called Australian Action on Preeclampsia,” he said.
“[They] recently conducted a survey of women asking them about their experiences of preeclampsia. And the resounding message that came through was that women basically didn’t know about preeclampsia, or the possibility of preeclampsia, until it occurred in their pregnancies.
“Often they feel very guilty about not presenting earlier, or not paying attention to some of the symptoms that they were troubled by.”
In the early pregnancy assessment, it is important that GPs explain the symptoms of preeclampsia (swelling of hands, feet and face, dizziness, headaches and vision problems in severe cases) so women know what to look out for.
When a woman presents with high blood pressure, there are also now predictive blood tests to detect the imbalance of angiogenic and anti-angiogenic markers in a woman’s bloodstream (soluble fms-like tyrosine kinase 1 to PlGF ratio).
“These can, in a woman with high blood pressure but no other signs of preeclampsia, both help rule out imminent preeclampsia and also help identify some women at high risk of an adverse outcome from preeclampsia in the next week,” said Associate Professor Henry.
“This test should generally be done within the hospital or day assessment setting rather than the GP practice.”
This test is also currently the subject of an MSAC submission to be added to Medicare.
Future treatments and long term health after preeclampsia
Although there are no current treatments for preeclampsia, there has been some promising research. A recent South African study, published in the BMJ, looked at whether slow release metformin could prolong pregnancy compared with placebo.
“We showed that indeed, metformin did prolong gestation of women with preeclampsia,” said Dr Brownfoot, who was a co-author on the study.
“There was also some suggestion that it improved neonatal outcomes as well. But we now need a much bigger study to see whether or not these findings will hold.”
Unfortunately, the effects of preeclampsia don’t always end once the pregnancy is over.
“Women have at least a doubled risk of cardiovascular disease and type 2 diabetes, triple the risk of chronic hypertension, and five to ten times the risk of chronic kidney disease after preeclampsia versus normotensive pregnancy,” said Associate Professor Henry.
It’s not just mothers at risk.
“There are also associations with increased cardiovascular and metabolic disease in children after preeclampsia, with higher blood pressure and weight noted as early as late childhood,” she said.
For GPs, it is important to assess a patient’s cardiovascular risk factors within the first postpartum year, encourage risk-reducing lifestyle behaviour change and treat any chronic hypertension.
With May being Preeclampsia Awareness Month, it’s important that pregnant women are aware of the disorder and have access to the promising preventive treatments in order to improve outcomes for mothers and their babies.
For more information:
- Review article of preeclampsia from the New England Journal of Medicine, 2022
- The Fetal Medicine Foundation – Preeclampsia
- Australian Government Pregnancy Care Guidelines – Risk of Preeclampsia
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