Preeclampsia/Hypertensive disorders of pregnancy
Hypertensive disorders of pregnancy are the most common and dangerous pregnancy complications where both mother and fetus may be severely affected.
Definitions and epidemiology
Hypertension, defined as a blood pressure exceeding 140 mmHg (systolic) and/ or 90 mmHg (diastolic), affects approximately 10% of pregnancies world-wide.
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Chronic hypertension in pregnancy affects 1-2% of pregnancies in the Nordic countries. It is defined as hypertension detected before the pregnancy, or during first 20 weeks of pregnancy (women normally decrease their blood pressure in the first trimester). Some of women with chronic hypertension will also develop proteinuria and their pregnancy is then characterized with “superimposed preeclampsia”.
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Gestational hypertension (GH, in Europe also named pregnancy induced hypertension-PIH) affects 4-5% of pregnancies in Norway, and is defined by new-onset hypertension presenting after gestational week (GW) 20. About 20% of GH pregnancies will later in pregnancy develop proteinuria, and therefore the pregnancy is defined as preeclamptic.
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Preeclampsia(PE) affects approximately 3-4% of pregnancies in the Nordic countries and is traditionally defined as new-onset hypertension and proteinuria detected after GW 20. As researchers and clinicians are now acknowledging the clinical heterogeneity of preeclampsia, women with new-onset hypertension after GW 20 can also be defined as preeclamptics without new-onset proteinuria, in the situation where she also has new onset of other preeclampsia-related signs, such as HELLP (hemolysis, elevated liver enzymes, low plates), eclampsia, visual/cerebral affection etc.
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Eclampsia is a rare form of preeclampsia, affecting 5 in 10 000 pregnancies in Scandinavia. It is defined as general seizures that occur during pregnancy (40%), delivery (30%) or the first week after delivery (30%), when it coexists with a hypertensive pregnancy disease and where there is found no other neurological causes for the seizure. Magnesium sulphate is the drug of choice.
Pathophysiology of preeclampsia
Preeclampsia requires the presence of placenta tissue, but the maternal predisposition (e.g. obesity, chronic hypertension, chronic renal disease, multiple pregnancy etc) also plays a significant role. For some, especially the early-onset for of preeclampsia with preterm delivery, there is an incomplete development of the maternoplacental circulation (spiral arteries). Central to the development of the maternal disease is an excessive systemic maternal vascular inflammation with vascular (endothelial) dysfunction, secondary to inflammatory substances shed from a dysfunctional placenta (due to malperfusion of the placenta). Preeclampsia is syndromic in its nature, explained by its widespread effect on many organs.
Symptoms and signs
The following SYMPTOMS (patient subjective) or SIGNS (objective findings) may indicate severe features of preeclampsia (and are therefore indications for contacting the doctor/hospital).
| Symtoms | Clinical signs | Lab | Explanation: why could preeclampsia (PE) cause this? |
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| Severe headache, visual disturbance/flashes | Foot clonus | | May indicate prodromal stage of eclampsia |
| Reduced fetal movements | Adverse CTG/ Doppler | | May indicate severe placental dysfunction (frequent in early-onset preeclampsia, but also possible at term preeclampsia) |
| Strong abdominal pain | | Elevated liver enzymes, low platelets, signs of hemolysis (LD) | Epigastric or upper right quadrant: may indicate HELLP (hemolysis, elevated liver enzymes, low platelets)/ liver disease or rupture.
Any part of the abdomen: may indicate abruptio placenta (detachment of the placenta prior to delivery: the risk of this in preeclampsia is elevated due to placenta pathology) |
| Very rapid weight gain | Very severe hand/leg and face edemas | Elevated hematocrit | Severe preeclampsia pathology includes severe endothelial dysfunction and excessive leakage of fluid into tissues |
| Dyspnoa | Abnormal lung sounds (rales, crackles) | Decreased oxygen saturation | Preeclampsia increases the risk of lung edema, same reason as above.
Also increased, is the risk of deep venous thrombosis/lung embolus due to higher thrombosis predisposition due to excessive activation of the endothelium.
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| Vascular shock | Excessive maternal hemorrhage during/after delivery | Decreased fibrinogen platelet levels and platelet counts
| Increased risk of bleeding due to low platelet counts as well as platelet dysfunction (either isolated, or part of HELLP), secondary to microcirculation and endothelial dysfunction |
Patient information
Do you know what to do if you measure hypertension and proteinuria in a pregnant woman? When to refer her to the hospital? What to tell her?
This film may illustrate some of the key points. Antihypertensive therapy is started in women with preeclampsia when blood pressure is ≥ 150/100.
Film: Preeclampsia long-term follow-up”
“Film: Preeklampsi langtidsoppfølging
Are you able to answer the questions below from the patient? Some tips on how to respond are suggested.
• What is preeclampsia, and what is the role of the placenta?
Show tips
You may want to present some of the following key points:
- Preeclampsia is a pregnancy complication.
- Preeclampsia is identified (diagnosed) when a high blood pressure and proteinuria is present, or if high blood pressure is identified in combination with organ distress in the kidney, liver, brain, or hematological system.
- Preeclampsia very rarely presents before 20 weeks of pregnancy. Most often, the woman is not aware of her developing preeclampsia, which is why regular antenatal check-ups in the second half of pregnancy is so important.
- The placenta plays an important role in preeclampsia. Our understanding today is that the blood flow inside the placenta is not normal. The placenta then becomes stressed, and releases stress factors into the mother’s circulation. These increased levels of stress signals will hit all vessels in the body, and result in maternal signs from the cardiovascular and renal systems in the form of hypertension and proteinuria.
- So, preeclampsia affects the whole body, and diverse complications may occur in some of the most severely affected pregnancies: such as eclampsia/seizures, stroke, liver-, kidney- and blood clotting disorders. Since the placenta is not functioning optimally, there is also some risk of the placenta detaching too early from the uterine wall, which we call placental abruption. These rare, but severe complications, are the reasons why we want you here in the hospital until you have delivered safely.
- In women who develop preeclampsia very early on in pregnancy, the placenta’s function may be very poor, and this can reduce the baby’s growth. In women who get preeclampsia closer to term, the fetus most often grows normally. In situations with very poor placental function, the fetus may die before delivery. This is very rare in preeclampsia developing at term, at least in this part of the world where we are lucky enough to have excellent health care.
- The only cure for preeclampsia today is to remove the placenta, which means delivering the fetus as well. Sometimes, delivery is needed very early in pregnancy, in order to save the mother’s and baby’s lives. Women who have reached 37 weeks of pregnancy are considered to be “at term”, and so delivery is induced in order to prevent development of any of the severe complications of preeclampsia. This induction is done to optimize the health of the mother and the fetus.
You may want to present some of the following key points:
- First of all, ANY pregnant women can develop preeclampsia.
- In Northern Europe, about 10% of all pregnancies have some sort of high blood pressure complication, either presenting before or during pregnancy. ONLY 3% of pregnant women develop preeclampsia, however, which is a specific type of hypertensive disorder.
- Some women are at a higher risk for preeclampsia than others. Women who are pregnant with their first child are at a higher risk than women who have previously had uncomplicated pregnancies. Other risk factors for preeclampsia are hypertension prior to pregnancy, renal disease, diabetes mellitus, and obesity. Also older women and women with a maternal family history of preeclampsia are at a higher risk, as are women who develop diabetes mellitus in pregnancy, or are pregnant with more than one fetus (such as twins). The reason for why first time pregnancy is a risk factor for preeclampsia is likely complex: There are several factors that affect how maternal and fetal cells interact and how the placenta is established. The cells from the placenta are fetal cells, and they express genes (as surface proteins) from the father that are different from the mother’s. The immune cells of the mother respond to these proteins.These placental cells help to remodel the maternal arteries in the uterine wall into wide vessels, so that the blood flow to the placenta is good. In subsequent pregnancies, this placentation process meets less resistance, as some of the uterine arteries remain wide in the next pregnancy, and it is likely that the maternal immune system is now better adapted to her partner. Therefore, there is usually less risk of developing placental problems and preeclampsia in a second pregnancy with the same partner (unless more than a 10 year period has passed since the previous pregnancy; in which case the risk is almost as in a first time pregnancy).
• How will you follow up my pregnancy given that I have preeclampsia?
Show tips
You may want to present some of the following key points:
- The important is to secure a safe delivery and good health for you and your baby.
- It is often recommended that a woman with preeclampsia is observed at the hospital until after delivery. Some women will be followed up intermittently as outpatients or in the community health service (if personnel skilled at managing preeclampsia are available). Usually, if everything is OK with the mother and baby, delivery is induced at term, namely at 37 weeks, in order to reduce the risk of complications of preeclampsia.
- Until induction of delivery, daily blood pressure measurements and registration of the baby’s heart beat (CTG) will be performed. There is no need to repeat the urine measurements of proteinuria every day, if it has already been verified and there is no other renal disease present. In women with preeclampsia, where the baby’s health is threatened, ultrasound assessments of fetal blood flow and wellbeing will be performed.
- The midwives and doctors will also ask if a woman with preeclampsia has any headaches or visual disturbances or abdominal pain, which could be symptoms of threatening complications, such as eclampsia and liver problems.
- When in hospital; blood samples are drawn to ensure that a woman with preeclampsia has not developed HELLP; a complication of preeclampsia. HELLP is the acronym for Hemolysis- meaning we a drop in hemoglobin because red blood cells are being destroyed. EL stands for ELevated liver enzymes and LP for low platelets. All these biochemical alterations are caused by changes in the vascular and organ systems in preeclampsia, most likely secondary to increased secretion of stress factors from the dysfunctional placenta.
- Some women with preeclampsia need cesarean delivery: If there are some alarming signs of the woman’s or the baby's health being threatened, induction for vaginal delivery will be started prior to 37 weeks’. Alternatively a cesarean section is performed. The doctors will recommend whatever is best for the situation for both the mother and the baby. The clinical situation may change rapidly in preeclampsia, therefore the clinical management may also change.
- All women with preeclampsia are kept under close surveillance in a setting offering appropriate clinical care.
- There are no specific medications that treat preeclampsia. However, it is important to use medication to lower very high blood pressures when they occur, this to reduce the risk of cerebral bleeding. Also, if a woman develops signs or symptoms of likely developing eclampsia (seizures during pregnancy or the first 7 days postpartum that are caused by preeclampsia), or in the unlikely case she develops full-blown eclamptic seizures, injection of magnesium sulphate is used to improve the outcome. And if any woman gets preeclampsia before 34 weeks’, and she needs to be delivered at a very premature stage, the woman is given corticosteroid injections to improve the lung maturation of her baby.
• How to prevent preeclampsia in next pregnancy?
Show tips
You may want to present some of the following key points:
- The only sure way to never get preeclampsia is to never get pregnant.
- It is hard to prevent the preeclampsia syndrome when we do not know all its causes, and there are many pathways leading to this syndrome.
- The risk of repeated preeclampsia in a woman’s next pregnancy is very low if the woman previously delivered with preeclampsia at term, and has no risk factors (no obesity, no chronic hypertension, no renal disease or diabetes etc).
- Women who have been delivered very early because of preeclampsia, and have had a growth restricted newborn, have the highest risk of developing preeclampsia in their next pregnancy.
- For women with hypertension or chronic diabetes, optimization of their health is recommended before attempting a next pregnancy, likewise with obese women.
- Low-dose aspirin is the best prophylactic medication available today for preventing preeclampsia. Aspirin will decrease the likelihood of preterm preeclampsia but is much less effective in reducing preeclampsia startiing later on in pregnancy. Women who have a high risk of preeclampsia are recommended to take low dose aspirin starting at 12 weeks’ gestation in a next pregnancy (to be taken before bedtime at night).
• Has preeclampsia long-term effects on my own health or my baby’s health?
Show tips
You may want to present some of the following key points:
- The patient may be offered a brochure (English or Norwegian) that explains some of the long-term risk for cardiovascular disease after preeclampsia, and that gives advice on future lifestyle and follow-up
- Women who have had preeclampsia are, on average, at higher risk of developing long-term health complications than women who were pregnant, but without preeclampsia. Such complications include chronic hypertension, stroke, myocardial infarction, and diabetes mellitus. Today, we do not know if preeclampsia only reveals a predisposition for these problems, or if preeclampsia and placental problems also contribute to this long-term risk of disease.
- In general, pregnancy is seen as a stress test for how much a woman’s body can cope with under stress. Seen from this perspective, preeclampsia is a pregnancy complication that warns about a higher risk of cardiovascular disease at a premature age.
- The highest risk of premature cardiovascular disease in the mother after preeclampsia is in women with repeated preeclampsia; or with very early-onset preeclampsia, potentially complicated by fetal growth restriction. If a woman has none of these risk factors, and her next pregnancy is without preeclampsia, then her risk of premature cardiovascular disease is hardly elevated at all. A woman’s risk of developing preeclampsia in her next pregnancy is also very low if she had preeclampsia at term without any severe features.
- 3 months postpartum is a good time to think about good family habits when it comes to food and general physical activity and there are some links to general recommendation in the brochure (English or Norwegian).
- Smoking and obesity is important to avoid, as they increase the cardiovascular risk. It is also important to keep a healthy lifestyle, including physical activity and avoiding obesity.
- A reasonable method of follow-up after preeclampsia is to measure the woman’s blood pressure at the postpartum control to confirm that she still remains normotensive.
- In addition to measuring the blood pressure screening for diabetes by measuring blood HbA1c (glycosylated hemoglobin) is indicated. As a group, women with a history of preeclampsia have a higher risk of developing type II diabetes, which is also a risk factor for cardiovascular disease.
- For future controls, regular blood pressure follow-ups are recommended, at least every third year (for example when performing routine pap smears for cervical cancer screening). In women who have a higher risk of cardiovascular disease (such as in obesity, diabetes etc), annual check-ups after preeclampsia may be indicated, including blood pressure measurements, blood lipid measurements, and HbA1c. For women with clinical signs of cardiovascular disease, follow-up by a cardiologist may be indicated. For all women, however, it is important to prevent long-term adverse health effects by having an active and healthy lifestyle.
Click for movie in English: Preeclampsia long-term follow-upKlikk for film på norsk: Preeklampsi langtidsoppfølging
Information brochure (for layman and health officers) on Preeclampsia and future health, in English or Norwegian.
Take-home messages: gestational hypertension /preeclampsia
- Any pregnant woman may develop gestational hypertension (GH) /preeclampsia (PE)
- Regular antenatal visits are essential for diagnosing GH/PE
- Antihypertensive therapy reduces risk for maternal cerebral hemorrhage, but does not treat the primary problem of placental dysfunction