From headaches to swelling, to ‘silent’ symptoms, pre-eclampsia presents itself in a variety of ways. Dr Nick Walker explains what to look out for and what can be done.
Marama*, 25 years old and expecting her first baby, went to see her midwife for a routine check-up on her estimated due date. She had had a normal pregnancy and was feeling well. As usual, her blood pressure was checked and her urine tested. Although she felt normal that day, her blood pressure was elevated and protein was present in her urine. Her midwife discussed these issues with an obstetrician at the local hospital; having then been reviewed there and advised to undergo labour induction, Marama consented and gave birth, without complication, to a healthy 8lb baby boy.
Tiffany* was 42 years old and had been trying for a baby for many years. Finally Tiffany had conceived a twin pregnancy, with assistance from her fertility specialist, by undergoing IVF. She visited her obstetrician regularly and scans showed that one of the twins was growing much more slowly than the other. At just 30 weeks gestation, she developed pain around her liver and felt very unwell; she was admitted to hospital and blood tests showed abnormal liver and kidney function. During two days of intense inpatient observation, her condition deteriorated further and her twins were born by emergency Caesarean section. The twin girls, despite being premature, were born in a stable condition, and with several weeks of care in a NICU, they went on to become healthy and well-grown babies. Tiffany was monitored for just one week, during which she made a speedy and full recovery.
Sunita* was 35 weeks into her first pregnancy when she started to get severe headaches. She scheduled an appointment with her GP, instead of her LMC, thinking she was suffering migraines. On the morning of her visit she also noticed much more swelling around her face and she could not remove her wrist bangles due to swelling of her hands. Her blood pressure was extremely elevated and she was immediately given tablets to try to bring it down while being sent to hospital. Upon admission to hospital, her blood pressure had actually become more elevated despite the medication and she was now experiencing a steady and increasing pain in her back. A monitor was placed on her abdomen to check the baby’s heart patterns: this clearly showed that her baby was in severe distress and she was advised that this was due to bleeding occurring underneath the baby’s placenta. By now she’d also had blood tests showing that her blood was not clotting properly. She was advised to give birth by emergency C-section under a general anaesthetic – this was then performed but was complicated by heavy blood loss and her lungs became saturated with fluid. She was kept in intensive care for three days to recover. She then required three different medications to keep her blood pressure at a safe level. Four weeks after the birth, she still needed to take these to keep her blood pressure controlled. Sunita’s baby girl weighed six and a half pounds and, due to the general anaesthetic administered to her mother, was sleepy for the first five minutes after the birth. The anaesthetic then wore off and she needed no extra care, proving to be a vigorous and healthy baby.
Despite these quite differing case histories, Marama, Tiffany and Sunita all experienced the same disease: pre-eclampsia.
Pre-eclampsia (PET) – also known as HOP (hypertension of pregnancy), GPH (gestational proteinuric hypertension) and pregnancy toxaemia – is a syndrome specific to human pregnancy. The symptoms (feelings noticed by a patient) and signs (objective measurements such as blood pressure and lab tests) vary from case to case. Two basic criteria form a diagnosis of PET - elevated blood pressure and the presence of protein in the urine. Additional findings which may indicate more severe forms of PET include those as described in these case histories: abnormal liver, kidney, and blood-clotting tests; foetal growth restriction; fluid retention in the lungs, abdomen or extremities; severe headaches; visual disturbances; or abdominal pain. In rare and severe cases, PET may progress to failure of the liver or kidneys, heart failure, cerebral haemorrhage (stroke) and death. Another rare complication is eclampsia, which is due to abnormal brain activity from excess fluid in the brain tissue and appears very similar to epileptic seizures. Also, the baby may be affected as the high blood pressure increases the risk of bleeding underneath the placenta, causing foetal distress and, rarely, death in utero.
In short, pre-eclampsia ranges from a mild problem to a life-threatening condition for mother and baby.
What is the cause of pre-eclampsia?
This is a subject of much research and debate, and the underlying biological basis for the disease is not completely understood. The presence of a pregnancy, specifically the placental tissue, is necessary for the development of pre-eclampsia. It is widely accepted that abnormal placental tissue develops early in the pregnancy, and this eventually starts to release toxic substances in the second and third trimesters. These substances in the maternal bloodstream are thought to be responsible for the symptoms and signs noted above, and the abnormally functioning placenta is also responsible for problems like foetal growth impairment seen in some cases. It is not the baby that causes pre-eclampsia, it is his or her placenta.
Most studies find that pre-eclampsia affects around 4% of all pregnancies. Fortunately, the more severe cases are
rarer, as an example – eclampsia (convulsions) affects just 1% of patients with pre-eclampsia.
Management, prevention and cure
A step towards prevention is possible by reducing or eliminating those risk factors listed above, for example reducing body-weight and optimising control of blood pressure and diabetes. Readers will notice that many risk factors are not able to be modified, such as maternal age or twins! Low dose aspirin, taken from early in the pregnancy, is known to be a preventative agent but the treatment benefit is small – it is estimated to reduce the risk by only about ten percent. Supplemental calcium tablets also have a small prevention benefit, but only in women with low dietary calcium. The mainstay of managing pre-eclampsia remains early detection through education of patients and regular antenatal care.
As for cure? Pre-eclampsia is easily and simply ‘cured’ by removing the cause of the disease – the placenta. This means delivering the baby thus ending the pregnancy, which is not generally a problem when the baby is near to the estimated due date. The art and science of managing pre-eclampsia becomes apparent when the disease occurs pre-term, when the risk of delivering the baby too early must be weighed against the risk of the disease making the mother and/or the baby more and more unwell. Principles of management when pre-eclampsia occurs pre-term (before 37 weeks gestation) include admission to hospital for intense observation of mother and baby, control of blood pressure when it is too elevated, regular blood tests to alert clinicians to any sign of deterioration, and planning just the right time and mode of delivery – all on a case-by-case basis! These decisions are complex, highly individualised to the circumstances and undertaken by a team of clinicians including midwives, obstetricians, physicians, anaesthetists and neonatal specialists in consultation with the woman and her family.
After baby is born, pre-eclampsia disappears without any long-term problems in almost all cases. With modern neonatal care, even babies born prematurely due to pre-eclampsia will usually have normal development through infancy. Similarly, even mothers who have suffered kidney or liver damage almost always make a full physical recovery with hospital-level supportive care. After severe cases, most maternity units would offer to review a woman after the pregnancy, to debrief what happened and to make plans for any future pregnancies.
Marama, Tiffany and Sunita all had in common the pregnancy disorder that is pre-eclampsia but each manifested in vastly different ways. The disease is variable, and serves as a constant threat for a pregnant woman and a constant challenge for clinicians providing care! Rest assured, however, that with the comprehensive maternity care available in New Zealand – you and your pregnancy are in good hands.
*Names have been changed.
Keeping a close eye
Pre-eclampsia may appear slowly or suddenly, and its course can be stable over time or deteriorate very rapidly; it is very difficult to predict how each case will go. It is usually (with good antenatal care) detected before symptoms develop, when blood pressure is found to be elevated and a urine ‘dipstick’ shows positive for protein in urine. This is one of the reasons why maternity visits become more frequent towards the end of pregnancy: the odds of an 'invisible' problem like pre-eclampsia increase towards and beyond baby's due date. Between visits, it is important that pregnant women have an awareness of the symptoms which may indicate pre-eclampsia, and the presence of these should trigger an urgent clinical review.
There are many risk factors for the development of pre-eclampsia, which include maternal age over 40 years, increased body weight, twin pregnancies, first pregnancies, and women with a previous pregnancy affected by pre-eclampsia or a strong family history of the disease. Certain medical conditions such as high blood pressure, type 1 or 2 diabetes, or chronic kidney disease very much increase the chance a pregnant woman will develop pre-eclampsia. Most clinicians would monitor such patients more frequently with a view to earlier detection and management.
Dr Nick Walker is a specialist obstetrician working in both public practice at National Women's Hospital and private practice in Mt Eden, Auckland. He divides his time between these roles and helping his wife in caring for their four young children.