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AnneliKivijärvi

Elevated Blood Pressure in Pregnancy (Gestational Hypertension, Pre-Eclampsia)

Essentials

Detection of pre-eclampsia as early as possible is one of the most important aims of prenatal care.
Gestational hypertension (i.e. pregnancy-induced hypertension) should be monitored.
- Hypertension in pregnancy is associated with maternal morbidity and perinatal morbidity and mortality.
Pregnant woman with pre-existing hypertension should be followed up.
- The risk of perinatal death is significantly higher in second or further pregnancies of mothers with pre-existing hypertension who develop superimposed pre-eclampsia than in primigravidas who develop pre-eclampsia.
Starting low-dose aspirin (100 mg/day) Antiplatelet Agents for Preventing Pre-Eclampsia in gestational week 12+0 is recommended for women belonging to risk groups.

Definitions

Pre-eclampsia is defined as hypertension appearing after the 20th gestational week (systolic pressure ≥ 140 mmHg or diastolic pressure ≥ 90 mmHg) and proteinuria.
If there is hypertension without proteinuria, the patient must have additionally at least one of the following: thrombocytopenia, elevated ALT levels, elevated creatinine levels, neurological symptoms (such as headaches, visual disturbances) or delayed foetal growth.
- Proteinuria (0.3 g/day) may occur in normal pregnancy; however, for the diagnosis of pre-eclampsia the level of proteinuria must be 0.5 g/day.
Gestational hypertension (i.e. pregnancy-induced hypertension) is defined as an increase in systolic pressure > 30 mmHg or an increase in diastolic pressure > 15 mmHg from baseline.
Chronic hypertension is hypertension existing before pregnancy or before the 20th gestational week.
At the onset of pre-eclampsia there may be a phase when the kidneys are not yet damaged and blood pressure may be increased without proteinuria.
Superimposed pre-eclampsia occurs when a woman with chronic hypertension develops proteinuria after the 20th gestational week (or, in the absence of proteinuria, if there is even only one of the additional factors listed above).
- As many as one in four pregnant women with chronic hypertension may develop pre-eclampsia. It predisposes to premature delivery, caesarean section, low birth weight and perinatal death.

Prevalence

Globally, the prevalence of hypertensive disorders in pregnancy is about 5.2-8.2%, and of gestational hypertension 1.8-4.4% and pre-eclampsia 0.2-9.2% http://www.nature.com/articles/hr2016126.
- Significant regional variation exists and even higher than the aforementioned prevalence rates are possible. Find out about local epidemiology.
Eclampsia (grand mal type seizures) is a very rare complication.

Blood pressure during pregnancy

In normal pregnancy systolic blood pressure remains slightly below the level before pregnancy most of the time.
Diastolic blood pressure remains below the level before pregnancy until the last trimester when it reaches the pre-pregnancy level.
Blood pressure decreases moderately in the second trimester in almost half of all gravidas.
This physiological change is not easily detected in antenatal care, and in most cases blood pressure seems to rise mildly and evenly throughout pregnancy.

Follow-up of blood pressure and urine protein in prenatal care Antithrombotic Therapy for Women Considered at Risk of Placental Dysfunction, Antiplatelet Agents for Preventing Pre-Eclampsia

It is important to check the baseline level within the first trimester and monitor the direction of changes during pregnancy.
Blood pressure must be measured at every visit; it can rise very quickly in a short time.
It should be measured on the bare upper arm after a rest of at least 15 minutes; for obese patients a cuff long and wide enough should be chosen.
Using a meter at home helps (particularly in tense persons); blood pressure < 135/85 mmHg is normal.
In the second trimester diastolic pressure > 85 mmHg is a risk factor, already.
Raised blood pressure also at night suggests increased risk.
Estimate carefully the risk of high blood pressure and pre-eclampsia at the beginning of pregnancy.
In cases of increased risk, follow-up must be intensified after the 20th gestational week (a 4-week interval is too long!).
Urine protein (chemical urinalysis) should be tested at every antenatal visit.
Teach patients with elevated blood pressure how to test their urine at home with dipsticks after the 24th gestational week (1-3 times per week depending on the severity of the situation).
Low-dose aspirin Antiplatelet Agents for Preventing Pre-Eclampsia at a dose of 100 mg at night should be started in gestational week 12+0(-16) for women with risk factors for pre-eclampsia (see Table T1) and continued until week 36+0.
Find out whether calcium intake is usually sufficient in the local context. Calcium supplementation may decrease the risk of pre-eclampsia in women with low calcium intake Calcium Supplementation during Pregnancy for Preventing Hypertensive Disorders.
- Low intake of milk products or calcium-supplemented foods: Ca 500 mg/day
- No intake of milk products or calcium-supplemented foods: Ca 1 000 mg/day

When to start low-dose aspirin in antenatal care (source: Current Care Guideline Raskaudenaikainen kohonnut verenpaine ja pre-eklampsia [Gestational hypertension and pre-eclampsia], Duodecim 2021, modified)

Any of the following	At least 2 of the following
Chronic hypertension	Primigravid
SLE or antiphospholipid antibody positive	Age ≥40 years
Chronic kidney disease	BMI > 30
Type 1 or 2 diabetes	Mother or sister with pre-eclampsia
History of:	Pregnancy with donated egg cells
Pre-eclampsia	An interval > 10 years between pregnancies
Placental insufficiency with foetal growth disturbance	Multiple pregnancy
Intrauterine death of placental origin	PAPP-A MoM < 0.4 in 1st trimester screening

Treatment of blood pressure during pregnancy Magnesium Sulphate for Eclampsia and Pre-Eclampsia, Altered Dietary Salt for Preventing Pre-Eclampsia, Bed Rest for Hypertension during Pregnancy, Energy and Protein Intake in Pregnancy, Calcium Supplementation during Pregnancy for Preventing Hypertensive Disorders, Planned Early Delivery Versus Expectant Management for Hypertensive Disorders from 34 Weeks Gestation to Term, Drugs for Rapid Treatment of Very High Blood Pressure during Pregnancy, Antiplatelet Agents for Preventing Pre-Eclampsia, Interventions for Preventing Excessive Weight Gain during Pregnancy, Adverse Effects of Hypertension Treatment during Pregnancy, Beta-Blockers for Mild to Moderate Hypertension in Pregnancy, Antihypertensive Drug Therapy for Mild to Moderate Hypertension during Pregnancy, Antithrombotic Therapy for Women Considered at Risk of Placental Dysfunction

Salt restriction and rest (sick leave)
Antihypertensive medication should be started after consulting a specialist doctor at a maternal health centre
- if the systolic blood pressure is ≥ 150 mmHg or the diastolic pressure is repeatedly ≥ 100 mmHg, or even at lower pressure levels (> 140/90 mmHg) if the patient has symptoms (e.g., headache, visual disturbances) and/or proteinuria and/or oedema
- often in even lower pressure levels if the woman has diabetes or chronic renal disease.
None of the antihypertensive drugs used increase foetal blood circulation Antihypertensive Drug Therapy for Mild to Moderate Hypertension during Pregnancy. Significantly lowered blood pressure may impair uterine circulation Adverse Effects of Hypertension Treatment during Pregnancy. The chosen drug must have been proven safe for the foetus.
A selective beta-blocker Beta-Blockers for Mild to Moderate Hypertension in Pregnancy, an alfa-beta-blocker labetalol Beta-Blockers for Mild to Moderate Hypertension in Pregnancy or a vasodilatating long-acting calcium channel blocker Drugs for Rapid Treatment of Very High Blood Pressure during Pregnancy may be used.
- The recommended first-choice drugs are labetalol 100-400 mg 3 times daily or nifedipine (10-30 mg twice daily as a sustained-release product).
ACE inhibitors, ATR blockers and diuretics should be avoided.
- ACE inhibitors and ATR blockers are contraindicated at 6 weeks, already.
The aim is to lower systolic blood pressure to < 150 mmHg and diastolic pressure to 80-100 mmHg.
- In women with diabetes, the targets are < 140/80 mmHg or < 130/80 mmHg, if there is diabetic or non-diabetic nephropathy associated with albuminuria (urine albumin/creatinine ratio > 30 mg/mmol) and the target is achievable without adverse effects.

Referral to prenatal outpatient clinics

Women who suffer from chronic renal disease, severe hypertension or hypertension of nephrological origin should be referred when planning pregnancy already.
Patients with pre-existing hypertension should be referred preferably in early pregnancy for checking their medication.
Women whose blood pressure is raised before the 24th gestational week should be referred for differential diagnosis between essential and secondary hypertension as early as possible.
Patients with gestational hypertension and pre-eclampsia should be referred when either condition is detected Antenatal Clinics and Specialist Care: Consultations, Referrals, Treatment Guidelines.
Emergency referralAntenatal Clinics and Specialist Care: Consultations, Referrals, Treatment Guidelines
- Blood pressure ≥ 150-160/105-110
- Symptomatic pre-eclampsia
  - Abnormal headache not relieved by paracetamol
  - Visual disturbances (photophobia, bright flashing lights, black spots in the visual field or blurred vision)
  - Upper abdominal pain (typically on the right side)
  - Malaise, nausea, vomiting and restlessness
  - Dyspnoea
  - Rapidly increased swelling of the face and upper trunk, in particular (with simultaneously decreased urine output)
- Concern about how the foetus is doing
Treatment should be planned and followed up in specialized care (in addition to what is done at visits to the maternal health centre).
In about one patient in three, pre-eclampsia will get worse, causing most commonly severe hypertension, renal failure or the HELLP syndrome (haemolysis, elevated liver enzymes and low platelet count).
Hypertension involves a risk of placental failure and delayed foetal growth.
The need for planned delivery should be assessed.

Postnatal follow-up

Blood pressure and pulse rate are followed up at the hospital. Medication can be decreased as soon as blood pressure stays at ≤ 135/85 mmHg.
At the postpartum checkup, blood pressure and urine proteins should be measured; these should return to normal by 6-12 weeks after delivery.
- The blood pressure target is < 140/90 mmHg (< 135/85 mmHg measured at home).
- Patients should be informed about the risks associated with any future pregnancies and about how to follow up their health.
- They should be given lifestyle guidance concerning a healthy diet, physical exercise, not smoking, weight management, etc.
- For overweight or obese people, weight loss should be recommended
Pre-eclampsia and gestational hypertension involve an increased risk of later cardiovascular disease or type 2 diabetes.
- The risk of cardiovascular disease is 2-6-fold compared to women without pre-eclampsia.
- Abdominal obesity (waist circumference > 87 cm), in particular, is harmful.
In women with a history of hypertension who are on antihypertensive medication, the medication used before pregnancy can be resumed after delivery.
- Use of ATR blockers or thiazides is not recommended during breastfeeding.
If blood pressure has normalized, it should be followed up annually and medication started as necessary.
If blood pressure is elevated at the postpartum checkup, the patient should be referred for regular long-term follow-up.
- Blood pressure, BMI, blood glucose and lipids should be monitored.

Indications for referral for further examinations in specialized care from the postpartum checkup

Indications for referral for an antiphospholipid antibody test and consultation of the outpatient clinic of internal diseases or haematology to exclude the antiphospholipid syndrome*
Early pre-eclampsia (delivery before gestational week 34+0) or severely delayed foetal growth (< -2 SD), HELLP or thrombocytopenia alone (blood platelets < 80 × 10⁹ /litre)
Recurrent miscarriage in the first trimester
Foetal death (fetus mortus) in the second or third trimester, and placental infarction
Indications for referral to an outpatient clinic of internal medicine or endocrinology to exclude secondary hypertension
Blood pressure still elevated (140-160/90-100 mmHg), and critical values occurring at times (> 170/110 mmHg)
Symptomatic hypertensive crises (emergency referral)
In addition to hypertension, hypokalaemia, hypercalcemia, tachycardia and sweating
Indications for referral to an outpatient clinic of internal medicine or nephrology to exclude nephropathy
Proteinuria continuing after pregnancy with pre-eclampsia, or haematuria

*The first sample can be drawn on the maternity ward
Source: Current Care Guideline Raskaudenaikainen kohonnut verenpaine ja pre-eklampsia [Gestational hypertension and pre-eclampsia], Duodecim 2021 (modified)

References

NICE guideline. Hypertension in pregnancy: diagnosis and management. Published 25 June 2019. http://www.nice.org.uk/guidance/ng133

Bramham K, Parnell B, Nelson-Piercy C et al. Chronic hypertension and pregnancy outcomes: systematic review and meta-analysis. BMJ 2014;348():g2301. [PubMed]

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