The cause of preeclampsia and who will develop hypertension in pregnancy has puzzled health professionals for decades, but now the Director of Anaesthesia Research at the Royal Women’s Hospital (the Women’s) may have found some answers.
A/Prof Alicia Dennis and co-author Dr Julian Castro, a consultant cardiologist at St Vincent’s Hospital, wrote in the international journal Anaesthesia today that the cause of the potentially deadly condition of preeclampsia may be the unique response of women to the oxygen demands of a growing fetus.
The authors believe that pregnancy is uneventful in women who are able to maintain a sustained, balanced oxygen supply to meet the changing metabolic demands of the fetus. It is when a woman has a reduced capacity to provide oxygen to the fetus that it can become deadly to mother and baby.
Their new unified theory of preeclampsia challenges the current view that preeclampsia is caused specifically by a problem with the placenta. It also challenges the widely held view that preeclampsia is caused by an as yet unidentified substance that the placenta produces. It proposes that there are many different conditions either in the mother, in the placenta or in the baby that lead to inefficient oxygen delivery to the baby. The response of the mother is to try and deliver more oxygen to the baby to help the baby grow but in doing so this causes the problem of high blood pressure and damages her own body.
“Hypertension, or high blood pressure, in pregnant women remains a serious global problem affecting around 13 million women a year,” A/Prof Dennis wrote in the editorial that analysed research papers from across the world.
“There has been no decrease in the prevalence of preeclampsia over the last 50 years. We were looking for a unified theory to explain why so many pregnant women developed this condition.”
The authors said that reducing the number of deaths in preeclampsia started with demystifying this common cardiovascular consequence of pregnancy.
A/Prof Dennis said in the Anaesthesia editorial that if the effects of the condition and its treatment were better understood in the clinical setting, there would be fewer deaths caused by this problem.
A/Prof Dennis said untreated preeclampsia could be fatal for mothers and babies or cause serious health complications, including seizures, kidney failure, heart failure and haemorrhage.
One in four women with uncomplicated hypertension in pregnancy will develop preeclampsia and it is more common in women carrying twins or triplets, women who are obese or women with diabetes.
There is no accurate test to determine which pregnant women will develop the condition. The authors suggest there is an urgent need to apply the same standards of management, especially the use of cardiac ultrasound (echocardiography), in pregnant women as are used in non-pregnant adults with life-threatening heart disease.
A/Prof Dennis said preeclampsia could do with a name change.
“Referring to it as hypertension caused by pregnancy, rather than the historically out-dated name of preeclampsia, would mean that women worldwide could be better informed and counselled about the condition,” she said.
A/Prof Alicia Dennis is also a Staff Specialist Anaesthetist at the Women’s and Clinical Associate Professor, Departments of Pharmacology and Obstetrics & Gynaecology, at the University of Melbourne.