Pregnancy, Hypertension

Article Author:
Richard Luger
Article Editor:
James Arnold
Updated:
11/18/2018 8:33:15 PM
PubMed Link:
Pregnancy, Hypertension

Introduction

Hypertensive disorders of pregnancy, including chronic hypertension, with or without superimposed pre-eclampsia/eclampsia, gestational hypertension, or preeclampsia with or without severe features or eclampsia present a significant risk of morbidity to both mother and fetus. Although appropriate prenatal care with close observation to detect signs of pre-eclampsia and prompt delivery to reduce or avoid adverse effects have produced reduced morbidity and mortality, they still exist. While hypertension itself presents concerns during pregnancy, adverse effects from progression to pre-eclampsia/eclampsia present the primary concern. [1][2][3]

Etiology

Conditions that reduce uteroplacental blood flow and vascular insufficiency including pre-existing hypertension, renal disease, diabetes mellitus, thrombophilia, and autoimmune disease have demonstrated an increased risk for hypertensive disease in pregnancy. Additionally, women with a previous history of preeclampsia, previous history of HELLP syndrome, twin or other multiple pregnancies, obesity, autoimmune disease, are women who are less than 20 years of age or more than 40 years of age, are first-time mothers, or have a mother or sister who has had gestational hypertension have been shown to be at higher risk for developing gestational hypertension and are at an elevated risk of progressing to pre-eclampsia.[4][5]

Epidemiology

Hypertensive disorders complicate between 5% and 10% of all pregnancies. Pre-eclampsia complicates 3% of all pregnancies in the United States and 4% of pregnancies worldwide. The incidence of hypertension is increasing due to changes in maternal demographics (e.g. advancing maternal age, increased pre-pregnancy weight). Eclampsia, however, has declined due to improved prenatal care, and the increased use of antenatal therapies (e.g. blood pressure control, magnesium seizure prophylaxis) as well as timely delivery by induction of labor or cesarean section which serve as a cure for pre-eclampsia/eclampsia.[6][7]

Pathophysiology

The pathophysiology of hypertension in pregnancy is not completely understood. Current research demonstrates that improper trophoblast differentiation during endothelial invasion due to abnormal regulation and/or production of cytokines, adhesion molecules, major histocompatibility complex molecules, and metalloproteinases plays a key role in the development of a gestational hypertensive disease.  Abnormal regulation and/or production of these molecules leads to abnormal development and remodeling of spiral arteries in the deep myometrial tissues. This leads to placental hypoperfusion and ischemia. Antiangiogenic factors are released by placental tissue causing systemic endothelial dysfunction which can result in systemic hypertension. Organ hypoperfusion from endothelial dysfunction is most commonly seen in the eyes, lungs, liver, kidneys and peripheral vasculature. [8]

History and Physical

Physical exam findings commonly noted with both chronic and gestational hypertension are limited to systolic blood pressure above 140mmHg and/or diastolic blood pressure above 90mmHg. Severe range blood pressures are above 160mmHg systolic and/or 110mmHg diastolic. An increase in edema is frequently noted in women with pre-eclampsia. Those demonstrating severe features may demonstrate cerebral symptoms (unremitting/severe headache, altered mental status), visual symptoms (scotomata, photophobia, blurred vision, or temporary blindness/visual field defect), pulmonary edema (dyspnea or rales on examination), or hepatic impairment (right upper quadrant pain).

Evaluation

Chronic hypertension is diagnosed per USPSTF guidelines as an in-office measurement with a systolic blood pressure greater than 140mmHg or diastolic blood pressure greater than 90mmHg confirmed with either ambulatory blood pressure monitoring, home blood pressure monitoring, or blood pressure evaluation with serial office visits, or with a single blood pressure greater than 180mmHg systolic or 110mmHg diastolic with or without emergent symptoms. Clinical symptoms are usually only noted when blood pressure is greater than 180/110 and may signify end organ damage.[9][10][11]

Gestational hypertension is defined per ACOG guidelines as blood pressure greater than or equal to 140mmHg systolic or 90mmHg diastolic on two separate occasions at least four hours apart after 20 weeks of pregnancy when previous blood pressure was normal. Alternatively, a patient with a systolic blood pressure greater than 160mmHg or diastolic blood pressure greater than 110mmHg can be confirmed to have gestational hypertension if they have a similar pressure after a short interval. This is in order to ensure timely antihypertensive treatment.  As above, clinical symptoms are usually only noted when blood pressure is greater than 160/110 and may signify end organ damage.

Pre-eclampsia is defined per ACOG guidelines as meeting either above hypertension criteria with greater than or equal to 300mg urine protein excretion in a 24-hour period, a protein/creatinine ratio of greater than or equal to 0.3, or a urine dipstick protein reading of at least 1+ (only used if above methods are unavailable). In the absence of the above findings, patients meeting criteria for chronic or gestational hypertension and having new onset of severe features of pre-eclampsia meet criteria for the diagnosis of pre-eclampsia. Severe features are defined as cerebral symptoms (unremitting/severe headache, altered mental status), visual symptoms (scotomata, photophobia, blurred vision, or temporary blindness/visual field defect), pulmonary edema, impaired liver function as indicated by liver transaminases elevated to greater than twice the normal concentration, progressive renal insufficiency as demonstrated by serum creatinine greater than 1.1 or a doubling of serum creatinine in the absence of another renal disease, or a platelet count of less than 1.0x10^5/ml meet criteria for pre-eclampsia.  Any of these findings or a systolic blood pressure greater than 160mmHg or diastolic blood pressure greater than 110mmHg constitute severe features suggestive of end organ damage. Pre-eclampsia can be superimposed with chronic hypertension, or as an advancement along the spectrum of gestational hypertensive disease. Per ACOG guidelines, systolic blood pressure of greater than 160mmHg or diastolic blood pressure greater than 110mmHg on two separate readings at least four hours apart while the patient is on bed rest is also considered a severe feature.

Eclampsia refers to the pre-eclamptic patient who progresses to have generalized tonic-clonic seizures secondary to her untreated/undertreated pre-eclampsia. Eclampsia occurs in approximately 2-3% of women with severe features who are not receiving anti-seizure prophylaxis and up to 0.6% of women with preeclampsia without severe features. Maternal complications occur in up to 70% of women experiencing eclamptic seizures with maternal morbidity as high as 14%.

Treatment / Management

Treatment/management of gestational and chronic hypertension in pregnancy is always indicated when blood pressures are in the severe range (>160/110). Several studies recommend consideration for treatment of pressures in the mild to the moderately hypertensive range (140-160/90-110). Commonly used therapies include calcium channel blockers, beta blockers, and methyldopa. Thiazide diuretics can be continued if used to treat chronic hypertension before pregnancy. Hydralazine and clonidine have been used in certain circumstances, but are not commonly used in the longitudinal treatment of gestational or chronic hypertension.  ACE inhibitors, angiotensin receptor blockers, mineralocorticoid receptor antagonists, and nitroprusside, are teratogenic and thus contraindicated in pregnancy.[2][12][13]

If a patient is experiencing pre-eclampsia with severe features, magnesium seizure prophylaxis is indicated until after delivery, and the appropriate diuretic response is seen. If the EGA is between 24 0/7 weeks and 33 6/7 weeks and delivery are imminent due to pre-eclampsia, eclampsia, or other concerns, antenatal steroid therapy is indicated to promote fetal lung maturity. (note - some providers will administer steroids in pregnancies up to 35 6/7 weeks EGA.) 

When patients are diagnosed with chronic hypertension, gestational hypertension, or pre-eclampsia, increased monitoring is recommended as concern for intrauterine growth retardation, placental abruption and poor placental/umbilical blood flow are concerns. Up to twice weekly BP monitoring, frequently combined with the fetal non-stress test, amniotic fluid index evaluation, and laboratory evaluations may be indicated. Abnormal findings on any of these evaluations may indicate the need for early delivery.

Definitive treatment of gestational hypertension, pre-eclampsia and eclampsia are delivery. Maternal sequelae of gestational hypertension, pre-eclampsia, and eclampsia resolve rapidly after delivery. Fetal development/maturity must be weighed against potential hypertensive/pre-eclamptic risks when determining that preterm delivery is indicated. ACOG guidelines recommending scheduled delivery timing vary depending on the diagnosis. Delivery is indicated as early as at diagnosis after 34+0/7 weeks estimated gestational age (WEGA) in patients with pre-eclampsia with severe features, Patients with mild pre-eclampsia without severe features might safely delay delivery until 37+0/7 WEGA or time of diagnosis if after 37+0/7 WEGA. Patients with difficult to control hypertension without pre-eclampsia should be delivered at between 36+0/7 WEGA and 38+6/7 WEGA. If blood pressure is better controlled, delivery is indicated between 37+0/7 WEGA and 39+6/7 WEGA depending on diagnosis and whether the patient requires medication to control her blood pressure. Most maternal care facilities use these guidelines as a basis to determine appropriate delivery timelines for their hypertensive or pre-eclamptic mothers.

Differential Diagnosis

  • Antiphospholipid syndrome
  • Aortic coarctation 
  • Cushing syndrome
  • Eclampsia
  • Glomerulonephritis
  • Hydatiform mole
  • Conn syndrome
  • Hyperthyroidism
  • Malignant hypertension

Complications

  • Eclamptic seizures 
  • Intracranial hemorrhage
  • Pulmonary edema
  • Renal failure
  • Coagulopathy

Enhancing Healthcare Team Outcomes

The management of hypertension in pregnancy is best done in a multidisciplinary team that consists of a cardiologist, obstetrician, dietitian, physical therapist, and nurse. The key is to prevent hypertension in the first place. While there is no one absolute way to prevent hypertension during pregnancy, it should encourage the patient to change lifestyle and become more physically active. The patient should eat healthy and avoid excess gain in weight. Regular follow up with the obstetrician is recommended and the patient should be taught how to monitor blood pressure at home. Smoking and alcohol should be avoided and the patient should try and avoid eating too many sugary foods. [11][14](Level V)

Outcomes

Development of hypertension during pregnancy is associated with high maternal and fetal morbidity and mortality. In the US, hypertension during pregnancy results in maternal mortality rates of 2-7% each year. Transient hypertension during pregnancy can lead to chronic hypertension development after pregnancy. Data also indicate that hypertension during pregnancy is associated with fetal growth restriction and placental abruption. [15][4](Level V)


References

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