What Is Pregnancy-Induced Hypertension?
PIH, also called gestational hypertension, is high blood pressure in pregnancy driven by vasospasm in both small and large arteries. Hypertensive disorders complicate roughly 5 percent to 8 percent of pregnancies (ACOG). The vasospasm raises vascular resistance and hinders blood flow to the liver, kidneys, brain, uterus, and placenta. It was once called toxaemia because researchers assumed a toxin produced in response to fetal protein caused the symptoms. No such toxin was ever found.
Pathophysiology
Cardiac output rises in pregnancy and can injure the epithelial cells of the arteries; the vasodilator prostaglandin may add to the injury. The vessels lose their normal responsiveness, vasoconstriction takes over, and blood pressure climbs.
Classifications
Gestational Hypertension
Elevated blood pressure (140/90 mmHg) with no proteinuria or edema. Perinatal mortality is not increased, so no drug therapy is needed. Look for systolic greater than 30 mmHg or diastolic greater than 15 mmHg above her pregnancy baseline. Pressure returns to normal after birth.
Mild Preeclampsia
Blood pressure of 140/90 mmHg or higher on two occasions at least 4 hours apart after 20 weeks of gestation in a woman who was previously normotensive (ACOG). Add proteinuria, defined as 300 mg or more in a 24-hour collection, a protein-to-creatinine ratio of 0.3 or more, or a dipstick reading of 1+ or 2+ when quantitative testing is unavailable. A weight gain over 2 lbs/week in the second trimester or 1 lb/week in the third usually signals abnormal tissue fluid retention.
Severe Preeclampsia
She has crossed into severe disease when blood pressure reaches 160 mmHg systolic or 110 mmHg diastolic or above on two occasions at least 4 hours apart while at bed rest (ACOG). Importantly, preeclampsia with severe features can now be diagnosed even without proteinuria once any severe feature appears, so do not wait on a urine result to act (ACOG). Watch for the severe features: thrombocytopenia (platelets under 100,000), impaired liver function or severe persistent right-upper-quadrant or epigastric pain, oliguria or a rising serum creatinine (above 1.1 mg/dL or doubled from baseline), pulmonary edema, and new cerebral or visual disturbances such as blurred vision or severe headache. Extensive edema may accompany this, visible as puffiness in the face and hands and most readily palpated over bony surfaces, though edema alone is no longer a diagnostic criterion.
Eclampsia
The most severe stage. Cerebral edema becomes acute enough to cause seizure or coma. Maternal mortality is high from cerebral hemorrhage, circulatory collapse, or renal failure, and fetal prognosis is poor from hypoxia and resulting fetal acidosis. Manifestations match severe preeclampsia, now with seizures.
HELLP Syndrome
A complication of severe preeclampsia or eclampsia: hemolysis (breakdown of red blood cells), elevated liver changes, and low platelets, leaving the blood unable to clot and control bleeding.
Risk Factors
Risk is higher with a first pregnancy (nulliparity), a multifetal gestation, and at the extremes of maternal age, both under 20 and over 35. A prior history of preeclampsia, obesity, chronic hypertension, pregestational diabetes, and kidney or autoimmune disease all raise risk as well (ACOG). Black women in the United States carry a disproportionately higher risk and worse outcomes. Limited access to nutrition and prenatal care can compound the picture.
Signs and Symptoms
Hypertension is the first indicator, a rise above her usual pressure. Proteinuria follows as protein leaks into the urine. Edema sets in once the protein that holds water inside the vessels has leaked out.
Diagnostic Tests
Urinalysis is the common test, detecting urinary protein that points to PIH.
Medical Management
Low-dose aspirin is recommended starting between 12 and 28 weeks (ideally before 16 weeks) for women at high risk, since platelets tend to cluster along vessel walls (ACOG). For acute severe-range pressures, labetalol, hydralazine, and oral nifedipine are the first-line antihypertensives. The cornerstone of preventing and controlling seizures in preeclampsia with severe features and in eclampsia is magnesium sulfate, the first-line agent, which roughly halves the rate of eclampsia (Eclampsia, StatPearls). A typical regimen is a 4 to 6 g IV loading dose over 20 to 30 minutes followed by a 1 to 2 g per hour infusion, with close monitoring of reflexes, respirations, and urine output for magnesium toxicity (keep calcium gluconate at the bedside as the antidote).
Surgical Management
No surgery is needed. PIH is managed with medications and nursing interventions.
Nursing Care Plan and Management
The nurse also drives the pressure down. The interventions are simple, but applied consistently they change outcomes: serial blood pressures, side-lying bed rest, a quiet environment, protein and urine output monitoring, and fast escalation when danger signs appear.
Frequently Asked Questions
What blood pressure defines gestational hypertension? Systolic of 140 mmHg or more or diastolic of 90 mmHg or more on two occasions at least 4 hours apart after 20 weeks of gestation in a woman who was previously normotensive (ACOG). Severe-range pressure is 160/110 mmHg or higher.
Do you need proteinuria to diagnose preeclampsia? No, not anymore. ACOG allows a diagnosis of preeclampsia with severe features without proteinuria once a severe feature appears, such as thrombocytopenia, impaired liver function, a rising creatinine, pulmonary edema, or new cerebral or visual symptoms (ACOG). Proteinuria still supports the diagnosis, but its absence no longer rules preeclampsia out.
What is the difference between preeclampsia and eclampsia? Eclampsia is preeclampsia that has progressed to seizures (or coma). It is the most severe stage and carries high maternal risk from cerebral hemorrhage, circulatory collapse, and renal failure, along with poor fetal outcomes from hypoxia.
Which drug prevents and controls seizures? Magnesium sulfate is the first-line agent for seizure prophylaxis in preeclampsia with severe features and for treating eclampsia, reducing the rate of eclampsia by about half (Eclampsia, StatPearls). Monitor reflexes, respirations, and urine output for toxicity and keep calcium gluconate available as the antidote.
What is HELLP syndrome? HELLP is a severe variant of preeclampsia or eclampsia marked by Hemolysis, Elevated Liver enzymes, and Low Platelets. The drop in platelets leaves the blood unable to clot and control bleeding, making it a true obstetric emergency.
What are the danger signs a patient should report immediately? A severe or persistent headache, visual changes such as blurring or spots, right-upper-quadrant or epigastric pain, sudden swelling of the face and hands, and decreased urine output. Any of these can signal the slide toward severe disease and eclampsia.