Medical School · Year 3 · Obgyn · includes a quiz and discussion video

Seminar 6: Hypertensive Disorders in Pregnancy

Year 3: Obstetrics and Gynecology Clerkship

Learning Objectives

By the end of this seminar, students will be able to:

1. Classify hypertensive disorders of pregnancy
2. Diagnose preeclampsia and assess severity
3. Manage preeclampsia and prevent seizures
4. Recognize and treat eclampsia
5. Identify HELLP syndrome
6. Describe postpartum hypertension management

Seminar Outline

I. Classification of Hypertensive Disorders

Hypertensive disorders of pregnancy encompass a spectrum of conditions that affect approximately 10% of pregnancies worldwide and represent a leading cause of maternal and perinatal morbidity and mortality. Chronic hypertension is defined as hypertension present before pregnancy or diagnosed before 20 weeks gestation, indicating a pre-existing condition unrelated to the pregnancy itself. Gestational hypertension refers to new-onset elevated blood pressure occurring at or after 20 weeks gestation without proteinuria or other features of preeclampsia. Preeclampsia represents a pregnancy-specific syndrome characterized by hypertension accompanied by proteinuria or other signs of end-organ dysfunction, while superimposed preeclampsia occurs when a woman with pre-existing chronic hypertension develops new proteinuria or other features of preeclampsia. Eclampsia is defined as the occurrence of generalized tonic-clonic seizures in a woman with preeclampsia that cannot be attributed to other causes.

Blood pressure measurement in pregnancy requires standardized technique with the patient seated, arm at heart level, and using an appropriately sized cuff to ensure accurate readings. Normal blood pressure in pregnancy is defined as systolic less than 120 mmHg and diastolic less than 80 mmHg, while elevated blood pressure falls between 120-129 systolic with diastolic less than 80 mmHg. Hypertension is diagnosed when systolic pressure reaches 140 mmHg or greater, or diastolic pressure reaches 90 mmHg or greater, and these readings must be confirmed on two separate occasions at least four hours apart. Severe hypertension is defined as systolic blood pressure of 160 mmHg or greater, or diastolic blood pressure of 110 mmHg or greater, and requires urgent treatment to prevent maternal stroke and other complications. The physiologic changes of pregnancy normally cause a decrease in blood pressure during the second trimester, which may mask underlying chronic hypertension if blood pressure measurements are only obtained mid-pregnancy.

Proteinuria assessment remains an important component of preeclampsia diagnosis, though it is no longer required when severe features are present. The gold standard for quantifying proteinuria is a 24-hour urine collection with protein excretion of 300 mg or greater considered abnormal. A spot urine protein-to-creatinine ratio of 0.3 or greater correlates well with significant 24-hour protein excretion and provides faster results for clinical decision-making. Urine dipstick testing showing 2+ protein may be used only when quantitative methods are unavailable, as dipstick results are subject to variation based on urine concentration and other factors. Importantly, the absence of proteinuria does not exclude preeclampsia if other severe features are present, as some women develop end-organ dysfunction without demonstrable proteinuria.

Multiple risk factors have been identified that increase a woman's likelihood of developing preeclampsia during pregnancy. Nulliparity represents a significant risk factor, with first pregnancies carrying higher risk than subsequent pregnancies with the same partner. Prior preeclampsia is the strongest predictor of recurrent disease, with recurrence rates ranging from 20-40% depending on the severity of the initial episode and gestational age at onset. Multiple gestation increases risk due to greater placental mass and higher placental-derived factors that contribute to the pathophysiology. Chronic hypertension, pregestational diabetes, obesity, advanced maternal age over 35 years, autoimmune diseases such as systemic lupus erythematosus and antiphospholipid syndrome, and chronic kidney disease all represent additional risk factors that should prompt heightened surveillance during prenatal care.

<image>Panel A: Classification diagram showing the five hypertensive disorders of pregnancy with their defining criteria and relationships. Panel B: Blood pressure measurement technique demonstrating proper patient positioning, cuff placement, and threshold values for diagnosis. Panel C: Proteinuria assessment flowchart showing progression from dipstick screening to 24-hour collection or protein/creatinine ratio. Panel D: Risk factor assessment showing maternal, pregnancy-related, and medical history factors that increase preeclampsia risk.</image>

II. Preeclampsia

The pathophysiology of preeclampsia centers on abnormal placentation that occurs during the first trimester and early second trimester of pregnancy. In normal pregnancy, extravillous trophoblast cells invade the decidua and myometrium, remodeling the spiral arteries into low-resistance, high-capacity vessels that allow adequate blood flow to the developing placenta. In preeclampsia, this spiral artery remodeling is incomplete, resulting in narrow, high-resistance vessels that deliver insufficient blood flow and cause placental ischemia. The ischemic placenta releases various factors including soluble fms-like tyrosine kinase-1 (sFlt-1) and reduced placental growth factor (PlGF), creating an angiogenic imbalance that leads to widespread maternal endothelial dysfunction. This endothelial dysfunction affects multiple organ systems including the kidneys, liver, brain, and vascular system, explaining the diverse clinical manifestations of the disease.

Preeclampsia without severe features is diagnosed when a pregnant woman at or beyond 20 weeks gestation develops hypertension with blood pressure of 140/90 mmHg or greater on two occasions at least four hours apart, accompanied by proteinuria of 300 mg or greater in a 24-hour urine collection or a protein-to-creatinine ratio of 0.3 or greater. These women do not manifest any of the severe features described below and typically present with milder disease that may be managed expectantly under close surveillance. The gestational age at diagnosis significantly impacts prognosis and management, with earlier onset disease generally associated with worse maternal and fetal outcomes. Women with preeclampsia without severe features still require close monitoring as the disease can progress rapidly to develop severe features at any time.

Severe features of preeclampsia indicate significant end-organ dysfunction and mandate more aggressive management including consideration for delivery. Severe-range blood pressures are defined as systolic pressure of 160 mmHg or greater, or diastolic pressure of 110 mmHg or greater, and require urgent antihypertensive treatment to prevent stroke. Thrombocytopenia with platelet count below 100,000 per microliter reflects the microangiopathic process affecting the maternal vasculature. Hepatic involvement manifests as elevated transaminases to twice the upper limit of normal, often accompanied by right upper quadrant or epigastric pain from liver capsule distension. Renal insufficiency is indicated by serum creatinine greater than 1.1 mg/dL or a doubling of the baseline creatinine, while pulmonary edema and cerebral or visual symptoms such as severe headache, altered mental status, or visual disturbances also constitute severe features.

Atypical presentations of preeclampsia can challenge diagnosis and require a high index of suspicion. Preeclampsia occurring before 20 weeks gestation is rare and should prompt investigation for molar pregnancy, multiple gestation, or antiphospholipid syndrome as underlying causes. The syndrome can occur without proteinuria when severe features are present, and clinicians should not withhold the diagnosis simply because proteinuria is absent if other criteria are met. Postpartum preeclampsia may develop de novo or worsen in women who had antepartum disease, with onset possible up to six weeks after delivery though most cases occur within the first week. These atypical presentations require clinicians to maintain vigilance for preeclampsia in any pregnant or recently postpartum woman presenting with symptoms of headache, visual changes, right upper quadrant pain, or sudden-onset severe hypertension.

<image>Panel A: Pathophysiology illustration showing normal versus abnormal spiral artery remodeling with corresponding angiogenic factor imbalances. Panel B: Clinical criteria diagram for preeclampsia without severe features showing blood pressure thresholds and proteinuria requirements. Panel C: Severe features checklist with organ systems affected including cardiovascular, hematologic, hepatic, renal, pulmonary, and neurologic. Panel D: Atypical presentation scenarios including early-onset, postpartum, and preeclampsia without proteinuria.</image>

III. Preeclampsia Prevention

Low-dose aspirin prophylaxis represents the most effective preventive strategy for reducing preeclampsia risk in women with identified risk factors. Women with high-risk factors including prior preeclampsia, multiple gestation, chronic hypertension, pregestational diabetes, or chronic kidney disease should receive aspirin prophylaxis. Women with two or more moderate-risk factors such as nulliparity, obesity with BMI greater than 30, family history of preeclampsia in a first-degree relative, advanced maternal age over 35 years, or socioeconomic factors associated with increased risk should also receive prophylaxis. The recommended dose is 81 mg (low-dose aspirin) taken daily beginning between 12 and 16 weeks gestation and continued until delivery. Studies demonstrate approximately 15-20% reduction in preeclampsia incidence with this intervention, with greater benefit observed when aspirin is initiated before 16 weeks and taken consistently.

Calcium supplementation has demonstrated modest benefit for preeclampsia prevention specifically in populations with low dietary calcium intake. The recommended dose for women with inadequate dietary calcium is 1.5 to 2 grams daily throughout pregnancy. Populations in developing countries with traditionally low calcium intake have shown the greatest benefit from supplementation, while women in developed countries with adequate dietary calcium intake derive minimal additional benefit. Calcium supplementation is considered safe in pregnancy and carries additional benefits for maternal bone health, though it should not be considered a substitute for aspirin prophylaxis in high-risk women who meet criteria for both interventions.

Several interventions that were once thought to prevent preeclampsia have been shown to be ineffective in well-designed clinical trials. Bed rest, previously commonly recommended, has not been shown to prevent preeclampsia and may increase the risk of thromboembolic complications in addition to causing significant disruption to the patient's daily life. Salt restriction does not prevent preeclampsia and is not recommended, as sodium intake has not been linked to preeclampsia development. Supplementation with antioxidant vitamins C and E, based on the theory that oxidative stress contributes to preeclampsia pathophysiology, has shown no benefit in large randomized trials. Magnesium supplementation during pregnancy for prevention purposes has also not demonstrated efficacy, though it remains an important treatment for seizure prophylaxis in women with preeclampsia with severe features or eclampsia.

Emerging biomarkers and screening tests show promise for identifying women at risk for preeclampsia earlier in pregnancy. The ratio of sFlt-1 to PlGF has been validated as a useful tool for ruling out preeclampsia in women presenting with suspected disease, with a low ratio having high negative predictive value. Uterine artery Doppler velocimetry demonstrating increased pulsatility index or bilateral notching in the first or early second trimester can identify women at increased risk, though this remains primarily a research tool. Blood pressure monitoring at each prenatal visit remains the foundation of screening, as hypertension typically precedes other manifestations of the disease. Future screening approaches may combine multiple biomarkers with maternal characteristics and blood pressure to improve prediction of women who will develop preeclampsia.

<image>Panel A: Aspirin prophylaxis algorithm showing high-risk and moderate-risk criteria with dosing recommendations and timing of initiation. Panel B: Calcium supplementation recommendations based on dietary intake assessment and population characteristics. Panel C: Evidence table showing ineffective interventions including bed rest, salt restriction, and vitamin supplementation with trial results. Panel D: Emerging screening methods including sFlt-1/PlGF ratio testing, uterine artery Doppler, and combined prediction models.</image>

IV. Preeclampsia Management

Management of preeclampsia without severe features depends primarily on gestational age at diagnosis and maternal and fetal status. Women diagnosed before 37 weeks gestation are typically managed expectantly with close monitoring, as the benefits of prolonging the pregnancy generally outweigh the risks of continuing expectant management. Monitoring includes blood pressure assessment at least twice weekly, laboratory evaluation including platelet count, liver enzymes, and creatinine weekly, and antenatal fetal testing. Outpatient management may be appropriate for reliable patients with mild disease, though hospitalization is often preferred for closer surveillance and to ensure rapid intervention if deterioration occurs. At 37 weeks gestation or beyond, delivery is recommended as the benefits of continuing the pregnancy diminish while the risks of disease progression increase.

Management of preeclampsia with severe features requires more intensive monitoring and earlier consideration of delivery. Women diagnosed before 34 weeks gestation at a tertiary care center with appropriate neonatal intensive care capabilities may be managed expectantly if maternal and fetal status are stable, allowing administration of antenatal corticosteroids and additional fetal maturation. Between 34 and 37 weeks, delivery is generally recommended after completion of a course of corticosteroids if not already administered, with the exact timing individualized based on disease severity. At 37 weeks or beyond, delivery should occur promptly regardless of disease stability. Women who are hemodynamically unstable, have evidence of end-organ deterioration, or demonstrate concerning fetal status should be delivered regardless of gestational age after maternal stabilization.

Antihypertensive therapy in pregnancy aims to prevent maternal stroke and other complications of severe hypertension while avoiding excessive blood pressure reduction that could compromise uteroplacental perfusion. First-line agents for chronic management include labetalol at doses ranging from 200 to 2400 mg daily in divided doses, and nifedipine extended-release at doses ranging from 30 to 120 mg daily. Hydralazine is typically reserved for acute severe hypertension rather than chronic management. The blood pressure goal is to maintain systolic pressure below 160 mmHg and diastolic pressure below 110 mmHg to prevent stroke, while avoiding excessive reduction that could compromise fetal perfusion. Angiotensin-converting enzyme inhibitors and angiotensin receptor blockers are contraindicated in pregnancy due to teratogenic effects including fetal renal dysplasia and oligohydramnios.

Acute severe hypertension with systolic pressure of 160 mmHg or greater or diastolic pressure of 110 mmHg or greater constitutes a hypertensive emergency requiring urgent treatment within 30 to 60 minutes. First-line treatment is intravenous labetalol starting with 20 mg bolus, which can be repeated with escalating doses of 40 mg then 80 mg at 10-minute intervals up to a maximum cumulative dose of 300 mg. Alternative agents include intravenous hydralazine 5-10 mg every 20 minutes or immediate-release oral nifedipine 10 mg, though nifedipine should be used cautiously in women who may require urgent cesarean delivery. The primary goal is to reduce blood pressure to below 160/110 mmHg to prevent maternal stroke, which represents a leading cause of death in women with preeclampsia. Continuous fetal monitoring should accompany acute blood pressure management, as rapid blood pressure reduction may transiently affect uteroplacental perfusion.

<image>Panel A: Management algorithm for preeclampsia without severe features by gestational age showing expectant management parameters and delivery timing. Panel B: Management of severe features showing indications for expectant management versus immediate delivery based on gestational age and stability. Panel C: Antihypertensive medication comparison showing dosing, onset, and contraindications for labetalol, nifedipine, and hydralazine. Panel D: Acute severe hypertension treatment protocol with step-by-step escalation and monitoring requirements.</image>

V. Magnesium Sulfate

Magnesium sulfate is the medication of choice for seizure prophylaxis in women with preeclampsia with severe features and for treatment and prevention of recurrent seizures in women with eclampsia. The indication for magnesium sulfate in severe preeclampsia is based on strong evidence demonstrating significant reduction in the risk of progression to eclampsia, with studies showing approximately 50% reduction in seizure risk. All women with severe features should receive magnesium sulfate during labor and delivery and for 24 to 48 hours postpartum, as this period represents the highest risk for seizure development. Women with eclampsia should receive magnesium sulfate as the primary treatment for seizure control and prevention of recurrence, as it has been shown to be superior to traditional anticonvulsants such as phenytoin and diazepam in this setting.

The standard loading dose of magnesium sulfate is 4 to 6 grams administered intravenously over 20 to 30 minutes, followed by a maintenance infusion of 1 to 2 grams per hour. In settings where intravenous access is not available or delayed, an intramuscular regimen may be used with a loading dose of 10 grams administered as 5 grams into each buttock, followed by 5 grams intramuscularly every 4 hours. The intravenous route is preferred in most clinical settings due to more predictable absorption and easier dose adjustment. Dose adjustments may be necessary in women with renal insufficiency, as magnesium is cleared by the kidneys and accumulation can occur with reduced creatinine clearance. Some protocols recommend reducing the maintenance infusion rate in women with oliguria or elevated creatinine to prevent toxicity.

The therapeutic serum magnesium level is 4 to 7 mEq/L (equivalent to 4.8 to 8.4 mg/dL), which provides optimal seizure prophylaxis while minimizing toxicity risk. Loss of deep tendon reflexes occurs at serum levels of approximately 10 mEq/L and serves as an important clinical warning sign of magnesium accumulation. Respiratory depression becomes a concern at levels of 12 to 15 mEq/L, and cardiac arrest can occur at levels exceeding 15 mEq/L. The wide margin between therapeutic and toxic levels makes magnesium sulfate a relatively safe medication when appropriate monitoring is performed, though vigilance for signs of toxicity remains essential throughout therapy.

Clinical monitoring during magnesium sulfate administration is essential to detect early signs of toxicity and ensure maternal and fetal safety. Deep tendon reflexes should be assessed hourly, as loss of reflexes indicates significant magnesium accumulation and should prompt holding the infusion and checking serum magnesium levels. Respiratory rate should be monitored continuously or at least hourly, with rates below 12 breaths per minute requiring immediate attention. Urine output should be measured hourly, as oliguria (less than 30 mL/hour) suggests potential accumulation and may require dose reduction. Mental status should be assessed regularly, as excessive sedation may indicate toxicity. Calcium gluconate 1 gram administered intravenously over 3 minutes is the antidote for magnesium toxicity and should be readily available at the bedside during magnesium sulfate administration.

<image>Panel A: Indications for magnesium sulfate showing severe preeclampsia features and eclampsia with evidence supporting use. Panel B: Dosing protocols for intravenous and intramuscular administration with loading and maintenance regimens. Panel C: Serum magnesium levels chart showing therapeutic range and toxicity thresholds with corresponding clinical manifestations. Panel D: Monitoring checklist showing assessment parameters, frequency, and intervention triggers with calcium gluconate antidote preparation.</image>

VI. Eclampsia

Eclampsia is defined as the occurrence of new-onset generalized tonic-clonic seizures in a woman with preeclampsia that cannot be attributed to another cause such as epilepsy, cerebral hemorrhage, or metabolic abnormalities. The timing of eclamptic seizures varies, with approximately 50% occurring antepartum, 25% intrapartum, and 25% postpartum, though postpartum eclampsia may occur up to several weeks after delivery. The risk of developing eclampsia in women with severe preeclampsia who do not receive magnesium prophylaxis is approximately 2%, underscoring the importance of prophylactic treatment. Seizures are typically generalized tonic-clonic in nature, lasting 60 to 90 seconds, and may be preceded by headache, visual disturbances, or right upper quadrant pain, though some women have no prodromal symptoms.

The differential diagnosis of seizures in pregnancy includes several conditions that must be considered, particularly when the presentation is atypical. Pre-existing epilepsy should be suspected in women with a history of seizure disorder, though eclampsia can occur in women with epilepsy and should not be excluded based on history alone. Cerebrovascular events including hemorrhagic stroke, ischemic stroke, and cerebral venous thrombosis can present with seizures and may coexist with or mimic eclampsia. Posterior reversible encephalopathy syndrome (PRES) shares pathophysiologic features with eclampsia and shows characteristic findings on MRI including bilateral occipital and parietal white matter edema. Central nervous system infections and metabolic derangements including hypoglycemia, hyponatremia, and hypocalcemia should also be considered in the differential diagnosis.

Management of an eclamptic seizure prioritizes maternal safety, airway protection, and prevention of recurrent seizures. The first step is protecting the patient from injury by positioning her in a lateral position if possible, lowering bed rails, and ensuring no hard objects are within reach. Airway management includes positioning the patient on her side to prevent aspiration, suctioning secretions as needed, and administering supplemental oxygen. Magnesium sulfate should be initiated immediately if the patient is not already receiving it, using the standard 4 to 6 gram loading dose, or an additional 2 gram bolus should be administered if she is already on magnesium and seizing. The fetus should be monitored after the seizure resolves, as fetal bradycardia commonly occurs during and immediately after seizures but typically resolves within 3 to 10 minutes; sustained abnormalities warrant evaluation. Delivery should be planned after maternal stabilization, though delivery should not occur during an active seizure.

Recurrent seizures despite adequate magnesium therapy require escalation of treatment and consideration of alternative diagnoses. An additional 2 gram bolus of magnesium sulfate should be administered for seizures occurring while on magnesium therapy, and serum magnesium levels should be checked to ensure therapeutic levels. If seizures persist despite adequate magnesium levels, intravenous lorazepam 4 mg or diazepam 5-10 mg should be administered. Status epilepticus, defined as continuous seizure activity or recurrent seizures without return to consciousness, may require intubation for airway protection and initiation of phenytoin or other anticonvulsant therapy. Neuroimaging with head CT should be strongly considered in women with recurrent seizures, atypical presentations, or focal neurologic findings to evaluate for intracranial hemorrhage or other structural abnormalities.

<image>Panel A: Eclampsia definition and timing distribution showing antepartum, intrapartum, and postpartum occurrence rates with risk factors. Panel B: Differential diagnosis table comparing eclampsia to epilepsy, stroke, PRES, infection, and metabolic causes with distinguishing features. Panel C: Step-by-step seizure management protocol including positioning, airway management, magnesium administration, and fetal monitoring. Panel D: Algorithm for recurrent seizures showing medication escalation, imaging indications, and intubation criteria.</image>

VII. HELLP Syndrome

HELLP syndrome is a severe variant of preeclampsia characterized by hemolysis, elevated liver enzymes, and low platelets, with the acronym representing these three cardinal features. Hemolysis is demonstrated by microangiopathic hemolytic anemia with abnormal peripheral blood smear showing schistocytes and helmet cells, elevated lactate dehydrogenase (LDH) greater than 600 IU/L, and elevated indirect bilirubin greater than 1.2 mg/dL. Elevated liver enzymes are defined as aspartate aminotransferase (AST) or alanine aminotransferase (ALT) elevated to at least twice the upper limit of normal, reflecting hepatocellular injury. Low platelets are defined as thrombocytopenia with platelet count below 100,000 per microliter. HELLP syndrome represents a point on the spectrum of severe preeclampsia, though some authorities consider it a distinct entity; importantly, up to 15% of women with HELLP syndrome may be normotensive at presentation, and many lack significant proteinuria.

The clinical presentation of HELLP syndrome often includes symptoms that may initially be attributed to other conditions, potentially delaying diagnosis. Right upper quadrant or epigastric pain is present in approximately 90% of cases and results from hepatic capsule distension due to sinusoidal obstruction and periportal hemorrhage. Nausea and vomiting are common presenting complaints and may be mistaken for gastroesophageal reflux, viral illness, or cholecystitis. Malaise and a general sense of feeling unwell often precede more specific symptoms. Because hypertension may be absent or mild in a significant proportion of cases, and proteinuria may not be present, HELLP syndrome should be considered in any pregnant woman presenting with right upper quadrant pain, nausea, or malaise in the second half of pregnancy, even in the absence of classic preeclampsia features.

HELLP syndrome carries significant risk of serious complications that contribute to maternal morbidity and mortality. Hepatic hematoma or rupture, though rare, represents a catastrophic complication with high mortality; presenting features include sudden severe right upper quadrant pain, shoulder pain, shock, and hepatic rupture can lead to exsanguination. Disseminated intravascular coagulation (DIC) may develop, manifested by prolonged prothrombin time, decreased fibrinogen, and elevated fibrin degradation products. Acute kidney injury from acute tubular necrosis occurs in a significant proportion of cases and may require dialysis support. Placental abruption risk is increased, and abruptio placentae may be the presenting feature. Maternal death, while uncommon with modern management, remains a risk particularly with delayed diagnosis or inadequate treatment.

Management of HELLP syndrome focuses on maternal stabilization followed by delivery, which is the definitive treatment. Initial stabilization includes correction of coagulopathy with blood products as needed, including packed red blood cells for anemia, platelets for severe thrombocytopenia (particularly if platelet count is below 50,000 per microliter and cesarean delivery is anticipated), and fresh frozen plasma if coagulopathy is present. Magnesium sulfate should be administered for seizure prophylaxis regardless of blood pressure, as women with HELLP syndrome are at significant risk for eclampsia. Antihypertensive therapy should be administered if blood pressure reaches severe range. Delivery should occur after initial stabilization, with route determined by standard obstetric indications; vaginal delivery is acceptable if maternal and fetal conditions permit, though cesarean delivery may be necessary for obstetric indications or rapidly deteriorating maternal status. Laboratory abnormalities typically worsen for 24 to 48 hours after delivery before beginning to improve.

<image>Panel A: HELLP syndrome diagnostic criteria showing laboratory thresholds for hemolysis (LDH, bilirubin, smear), elevated liver enzymes, and low platelets. Panel B: Clinical presentation features including right upper quadrant pain, nausea, malaise, and percentage of patients without hypertension. Panel C: Complications diagram showing hepatic hematoma/rupture, DIC, renal failure, abruption, and maternal death with relative frequencies. Panel D: Management algorithm including stabilization with blood products, magnesium sulfate, antihypertensives, and delivery planning.</image>

VIII. Chronic Hypertension in Pregnancy

Chronic hypertension in pregnancy is diagnosed when elevated blood pressure is documented before pregnancy or before 20 weeks gestation, indicating that the hypertension is not pregnancy-induced. The diagnosis can be challenging because blood pressure physiologically decreases during the second trimester due to peripheral vasodilation, potentially masking underlying chronic hypertension if blood pressure is not measured early in pregnancy or before conception. If hypertension persists beyond 12 weeks postpartum in a woman initially diagnosed with gestational hypertension or preeclampsia, the diagnosis should be changed to chronic hypertension. Many women enter pregnancy with undiagnosed chronic hypertension that only becomes apparent during prenatal care, emphasizing the importance of early pregnancy blood pressure assessment.

Medication management of chronic hypertension in pregnancy requires careful selection of agents that are safe for the developing fetus. Labetalol is the most commonly used first-line agent due to its established safety profile and effectiveness for blood pressure control during pregnancy. Nifedipine, particularly the extended-release formulation, is an appropriate alternative or second-line agent and is also used extensively in pregnancy. Methyldopa has the longest track record for safety in pregnancy and remains an option, though it is often less well tolerated due to side effects including sedation and depression. Angiotensin-converting enzyme inhibitors and angiotensin receptor blockers are absolutely contraindicated in pregnancy due to teratogenic effects including renal dysplasia, oligohydramnios, pulmonary hypoplasia, and fetal death; women taking these medications should discontinue them before conception or immediately upon pregnancy recognition. Atenolol should be avoided due to association with intrauterine growth restriction, and spironolactone is contraindicated due to anti-androgenic effects.

Treatment goals for chronic hypertension in pregnancy have evolved based on recent evidence. Severe-range hypertension with systolic pressure of 160 mmHg or greater or diastolic pressure of 110 mmHg or greater should be treated to prevent maternal stroke and other complications. For mild to moderate hypertension (systolic 140-159 mmHg or diastolic 90-109 mmHg), recent guidelines and the CHAP trial have supported treatment to a target of less than 140/90 mmHg, associated with improved pregnancy outcomes without increased risk of fetal growth restriction. The previous concern about excessive blood pressure reduction compromising uteroplacental perfusion has been somewhat mitigated by evidence showing safety of moderate blood pressure reduction. Women with chronic hypertension should have blood pressure monitored closely throughout pregnancy, with medication adjustments as needed to maintain goal blood pressure.

Superimposed preeclampsia develops in 20-50% of women with chronic hypertension and represents a significant complication requiring altered management. The diagnosis is made when a woman with chronic hypertension develops new-onset proteinuria after 20 weeks gestation, or experiences a sudden increase in proteinuria if baseline proteinuria was present. New onset of severe-range blood pressures after 20 weeks in a woman whose hypertension was previously well-controlled, or development of any severe features of preeclampsia including thrombocytopenia, elevated liver enzymes, renal insufficiency, pulmonary edema, or cerebral or visual symptoms also indicates superimposed preeclampsia. The management of superimposed preeclampsia follows the same principles as primary preeclampsia, with delivery timing based on gestational age and severity of disease. Women with chronic hypertension should be counseled about the increased risk of superimposed preeclampsia and instructed to report symptoms promptly.

<image>Panel A: Diagnostic criteria for chronic hypertension showing timing of diagnosis and differentiation from gestational hypertension. Panel B: Medication safety chart showing approved medications (labetalol, nifedipine, methyldopa) and contraindicated medications (ACE inhibitors, ARBs, atenolol). Panel C: Blood pressure treatment goals evolution showing previous conservative approach versus current evidence-based targets from CHAP trial. Panel D: Superimposed preeclampsia diagnostic criteria showing new-onset proteinuria, worsening hypertension, and development of severe features.</image>

IX. Gestational Hypertension

Gestational hypertension is defined as new-onset hypertension with blood pressure of 140/90 mmHg or greater occurring at or after 20 weeks gestation in the absence of proteinuria and without other features of preeclampsia. The blood pressure elevation must be confirmed on two separate occasions at least four hours apart to establish the diagnosis. Unlike chronic hypertension, there is no documented history of elevated blood pressure before pregnancy or early in the first trimester. By definition, gestational hypertension resolves by 12 weeks postpartum; if hypertension persists beyond this time, the diagnosis is reclassified as chronic hypertension.

The natural history of gestational hypertension includes a significant risk of progression to preeclampsia that must be considered in management planning. Approximately 25% of women diagnosed with gestational hypertension will progress to develop preeclampsia, with the risk being higher when gestational hypertension develops earlier in pregnancy. Women who develop gestational hypertension before 32 weeks gestation have progression rates approaching 50%, while those who develop hypertension later in pregnancy have lower progression rates. The progression to preeclampsia may occur rapidly and unpredictably, necessitating close surveillance for development of proteinuria, severe features, or symptoms suggestive of preeclampsia.

Management of gestational hypertension centers on surveillance for disease progression and timing of delivery. Blood pressure should be monitored frequently, with twice-weekly assessments in the outpatient setting for women with stable disease. Laboratory testing including complete blood count, liver enzymes, and creatinine should be performed regularly to detect early signs of preeclampsia. Antihypertensive therapy should be initiated if blood pressure reaches severe range (160/110 mmHg or greater) to prevent maternal complications. Fetal surveillance with antenatal testing is typically recommended given the increased risk of adverse perinatal outcomes. Delivery is recommended at 37 weeks gestation for women with stable gestational hypertension without progression to preeclampsia, as expectant management beyond this gestational age does not improve outcomes and carries continued risk of progression.

The postpartum period and long-term implications of gestational hypertension warrant attention and counseling. Blood pressure typically normalizes within the first few weeks postpartum, though some women require continued antihypertensive therapy during this period. If hypertension persists beyond 12 weeks postpartum, the diagnosis should be changed to chronic hypertension, and the woman should be referred for cardiovascular evaluation. Women with a history of gestational hypertension have increased long-term cardiovascular risk, with approximately two-fold increased risk of future chronic hypertension and increased risk of coronary heart disease and stroke compared to women with normotensive pregnancies. Counseling should address modifiable cardiovascular risk factors including weight management, physical activity, diet, and smoking cessation, with recommendation for regular blood pressure monitoring and primary care follow-up.

<image>Panel A: Gestational hypertension diagnostic criteria showing blood pressure thresholds, timing requirements, and absence of proteinuria/severe features. Panel B: Natural history diagram showing progression rates to preeclampsia based on gestational age at diagnosis. Panel C: Management protocol including blood pressure monitoring frequency, laboratory surveillance, and delivery timing at 37 weeks. Panel D: Postpartum and long-term outcomes including resolution timeline, reclassification criteria, and cardiovascular risk counseling.</image>

X. Postpartum Considerations

Postpartum preeclampsia represents an important and sometimes underrecognized clinical entity that can develop de novo or as worsening of antepartum disease. New-onset preeclampsia can develop at any point up to six weeks postpartum, though most cases occur within the first week after delivery. Symptoms include severe headache that is unresponsive to analgesics, visual disturbances such as scotomata or blurred vision, right upper quadrant or epigastric pain, and shortness of breath from pulmonary edema. All postpartum women should receive education about these warning signs and be instructed to seek immediate medical attention if symptoms develop. Women presenting with these symptoms should have blood pressure measured, laboratory studies obtained, and should be evaluated for preeclampsia even in the absence of antepartum disease.

Postpartum hypertension management requires appropriate medication selection and monitoring to achieve blood pressure control while allowing for breastfeeding if desired. Labetalol and nifedipine remain first-line agents and are considered compatible with breastfeeding, with minimal transfer to breast milk and no reported adverse effects in nursing infants. Methyldopa is also acceptable during breastfeeding. Nonsteroidal anti-inflammatory drugs, commonly used for postpartum pain control, should be used cautiously in women with hypertension as they may worsen blood pressure control and should be avoided in women with preeclampsia with renal insufficiency. Angiotensin-converting enzyme inhibitors have limited data in breastfeeding but are considered acceptable by some guidelines, particularly enalapril, which has minimal breast milk transfer; these agents may be appropriate for non-breastfeeding women or when first-line agents are ineffective. Diuretics at high doses should be avoided during breastfeeding as they may decrease milk production.

Magnesium sulfate administration in the postpartum period should continue for 24 to 48 hours following delivery in women who received it antepartum for preeclampsia with severe features or eclampsia. Women who develop postpartum preeclampsia with severe features should receive magnesium sulfate for seizure prophylaxis according to standard protocols. The postpartum period represents a high-risk time for eclampsia, with approximately 25% of eclamptic seizures occurring after delivery. Hospital discharge should not occur until blood pressure is controlled with oral medications, magnesium sulfate has been completed, and the patient demonstrates understanding of warning signs and has appropriate follow-up arranged. Readmission rates for hypertensive complications are significant, and many cases could potentially be prevented with appropriate education and accessible follow-up care.

Long-term counseling for women who have experienced hypertensive disorders of pregnancy should address both future pregnancy risks and lifetime cardiovascular health implications. The recurrence risk for preeclampsia in subsequent pregnancies ranges from 20-40%, with higher rates associated with more severe initial disease, earlier gestational age at onset, and underlying maternal conditions. Low-dose aspirin prophylaxis should be recommended in subsequent pregnancies starting at 12-16 weeks gestation. Beyond reproductive implications, women with a history of preeclampsia have two to four times increased lifetime risk of chronic hypertension, stroke, and ischemic heart disease compared to women with normotensive pregnancies. The American Heart Association recognizes preeclampsia as a cardiovascular risk factor, and women should be counseled about lifestyle modifications including maintenance of healthy weight, regular physical activity, heart-healthy diet, and smoking avoidance. Primary care follow-up for long-term blood pressure monitoring and cardiovascular risk assessment is essential.

<image>Panel A: Postpartum preeclampsia presentation showing warning symptoms, timing of onset, and patient education points. Panel B: Medication selection for postpartum hypertension with breastfeeding compatibility and contraindications. Panel C: Postpartum magnesium sulfate protocol showing duration, monitoring, and discharge criteria. Panel D: Long-term cardiovascular risk counseling including recurrence rates, aspirin prophylaxis for future pregnancies, and lifetime risk factor modification.</image>

Summary

• Preeclampsia is defined as hypertension at or after 20 weeks gestation with proteinuria or severe features including severe-range blood pressures, thrombocytopenia, elevated liver enzymes, renal insufficiency, pulmonary edema, or cerebral/visual symptoms
• Severe features requiring urgent intervention include blood pressure of 160/110 mmHg or greater, platelet count below 100,000, liver enzymes twice normal, creatinine greater than 1.1 mg/dL or doubled, and neurologic symptoms
• Low-dose aspirin prophylaxis at 81 mg daily starting between 12-16 weeks gestation reduces preeclampsia risk by 15-20% in women with high-risk or multiple moderate-risk factors
• Magnesium sulfate loading dose is 4-6 grams IV over 20-30 minutes followed by 1-2 g/hour maintenance for seizure prophylaxis in severe preeclampsia and eclampsia
• Magnesium toxicity manifests as loss of reflexes at 10 mEq/L and respiratory depression at 12-15 mEq/L, with calcium gluconate 1 gram IV as the antidote
• Acute severe hypertension requires treatment within 30-60 minutes with labetalol 20 mg IV (escalating to 40-80 mg) or hydralazine 5-10 mg IV, targeting blood pressure below 160/110 mmHg to prevent stroke
• HELLP syndrome includes hemolysis (LDH >600, abnormal smear), elevated liver enzymes (AST/ALT twice normal), and low platelets (<100,000), requiring stabilization followed by delivery
• Eclampsia management prioritizes airway protection, lateral positioning, magnesium sulfate administration, and delivery after maternal stabilization
• Gestational hypertension progresses to preeclampsia in approximately 25% of cases and requires delivery at 37 weeks if stable
• Postpartum preeclampsia can develop up to 6 weeks after delivery, and women with any hypertensive disorder of pregnancy have 2-4 times increased lifetime cardiovascular risk requiring long-term follow-up

Key Terms

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