Preeclampsia and Blood Pressure Issues in Pregnancy

Overview

High blood pressure, also known as hypertension, affects both men and women and contrary to popular belief, young people as well as older people. Here are several important categories of hypertensive disease in pregnancy.

Gestational hypertension: Patient has no problems with blood pressure before pregnancy but during pregnancy her blood pressure becomes elevated thought she does not develop preeclampsia.

Chronic Hypertension: Patient has blood pressure problems before pregnancy and continues with them through the pregnancy without worsening.

Chronic hypertension with superimposed preeclampsia: patient has blood pressure problems before pregnancy, but later in pregnancy worsens in her blood pressure values and also develops protein in her urine as well as other signs and symptoms constituting preeclampsia.

Mild preeclampsia: with or without pre-existing hypertension, a patient develops elevated blood pressures beyond their baseline, protein in their urine and other signs or symptoms, such as swelling.

Severe preeclampsia: with or without pre-existing hypertension, a patient develops greatly elevated blood pressures beyond their baseline, possibly protein in their urine and other specific severe signs or symptoms.

It is important to correctly classify hypertensive disorders in pregnancy, since only then is it possible to render the correct treatment.

Chronic hypertension

Chronic hypertension pregnancy is defined as hypertension present before 20 weeks gestation. It is associated with several adverse pregnancy outcomes, including premature birth, fetal growth restriction, placental abruption, stillbirth and need for cesarean delivery. This is the case because chronic hypertension in pregnancy, like all hypertension, damages blood vessels of all sizes. In pregnancy, this damage extends to the placenta which, after all, is a dense network of vessels.

Blood pressures are reported as two numbers, the systolic blood pressure over a diastolic blood pressure. In case you had ever wondered what this means, here is your explanation. The systolic blood pressure is the pressure of blood in the vessels when the heart is at the strongest part of it's pumping. That highest pressure depends not only upon the strength of the pump, but also the tension, or tone of the vessels. Blood vessels are like adjustable pipes which, under various hormonal, endocrine or immunologic influences, may contract or dilate. The diastolic blood pressure is the pressure of the blood in the vessel during the ebb, or lowest flow, of the cardiac stroke. This too is influenced by the degree of vascular tone.

Normal blood pressure for a woman typically include the systolic blood pressure under 130 mmHg and a diastolic blood pressure under 80 mmHg.
Mild chronic hypertension in pregnancy is defined as systolic blood pressure of 140 to 159 mmHg OR diastolic blood pressure of 90 to 109 mmHg.
Severe chronic hypertension in pregnancy is defined as systolic blood pressure of 160 mmHg systolic blood pressure OR diastolic blood pressure of 110 mm Hg or more, on more than one occasion, 4 to 6 hours apart.

Ideally patients with pre-existing pre-pregnancy hypertension would have it completely worked up and their treatment optimized before becoming pregnant. However in many cases patients do not have access to medical care before pregnancy, or they are unaware that they have a problem. In this instance one can simply hope for an early presentation to care when blood pressure values are at their pre pregnancy baseline, and complications of uncontrolled blood pressures have not yet had a chance to materialize.

Once a chronic hypertensive patient in early pregnancy is identified, she can be evaluated for treatment. Antihypertensive therapy has been shown to reduce the risk of a severe maternal hypertensive crisis but has not, through available studies, been shown to improve overall perinatal outcome. Experts in the United States have recommended that pregnant women with hypertension in the blood pressure range of 150–160/100–110 mm Hg should be treated with antihypertensive therapy, and that their blood pressure should be kept lower than 150/100 mm Hg.

Preeclampsia

Preeclampsia does not usually appear before 20 weeks of gestation. It is heralded by a sudden increase a blood pressure over baseline and most of the time, the appearance of protein in the urine. Preeclampsia can either be mild or severe. Mild preeclampsia can be managed expectantly whereas severe preeclampsia requires delivery. Both mild and severe preeclampsia share a list of risk factors.

Risk factors for preeclampsia (partial list) :

multifetal gestation

preeclampsia in a previous pregnancy

chronic hypertension

pregestational diabetes

vascular and connective tissue disease

nephropathy

antiphospholipid antibody syndrome

obesity, age of 35 years or older

African American race

Genetic and environmental factors

No one knows what really causes preeclampsia though insights are gained every year. I think of it as an immunologic and inflammatory reaction to the pregnancy which results in inflammation especially in the tiny blood vessels of the patients body. We call this a micro-angiopathy.

Criteria for the diagnosis of preeclampsia:

SBP ≥ 140 mm Hg systolic or DBP ≥90 mm Hg that occurs after 20 weeks of gestation in a woman with previously normal blood pressure

proteinuria ≥ 0.3 g protein or higher in a 24-hour urine specimen, which corresponds approximately to 1+ on a random urine dipstick

Management of mild preeclampsia

Gestational hypertension and mild preeclampsia before term may be managed with careful home observation with frequent and reliable clinic appointments, non stress tests and ultrasound. Women with difficulty with adherence or other logistical barriers to frequent follow-up should be hospitalized.Timing of delivery with chronic hypertension, gestational hypertension or mild preeclampsia is determined by standard obstetrical indications, with an eye toward delivery by 39 weeks if possible.

Severe preeclampsia

Blood pressure values may go into an extremely high range which may on their own, qualify a patient for the diagnosis of severe preeclampsia. Even if blood pressures do not go into this extremely high range, certain other signs and symptoms may qualify them for this diagnosis as well. For example, preeclampsia also may be associated with a myriad of other signs and symptoms, such as edema, visual disturbances, headache, and epigastric pain. Certain blood work values can become abnormal. Hemolysis (description of the red blood cells) , elevated liver enzymes, low platelets (HELLP) syndrome is a distinct and important version of severe preeclampsia called HELLP syndrome. Proteinuria may or may not be present in HELLP syndrome. Severe preeclampsia and HELLP syndrome are associated with an increased risk of adverse outcomes, including eclampsia (seizure) , abruption (premature separation of the placenta) , renal failure, subcapsular hepatic (liver) hematoma, preterm delivery, and even fetal or maternal death. The distinction between mild and severe preeclampsia is important for decisions regarding management and timing of delivery.

Management of severe preeclampsia

Management of severe preeclampsia should be accomplished at tertiary care center, with a Perinatologist or an experienced Obstetrician. Corticosteroids to accelerate fetal lung maturity may be given. Magnesium sulfate to prevent maternal seizures is also necessary. Depending on blood pressure values, specific blood pressure medication maybe given. The team will move towards delivery as soon as possible. C-section or vaginal delivery will be chosen depending on individual circumstances.

Excerpted and adapted from Guidelines for Perinatal Care, Seventh Edition, 2012

by the American Academy of Pediatrics and the American College of Obstetricians and Gynecologists.