Gestational Hypertension

• Placental insufficiency and abnormal trophoblastic invasion: In gestational hypertension, there is inadequate remodeling of the spiral arteries and failure of trophoblastic invasion to extend deeply into the myometrium. This results in increased placental vascular resistance, relative placental hypoperfusion, and activation of the placental-fetal unit to release pathogenic factors. The shallow implantation fails to convert the high-resistance spiral arteries into low-resistance vessels capable of accommodating the increased blood flow demands of pregnancy, leading to localized hypoxia and oxidative stress within the placental tissue.

• Release of placental antiangiogenic factors and endothelial dysfunction: In response to placental hypoperfusion, the syncytiotrophoblast releases excessive quantities of antiangiogenic factors, including soluble fms-like tyrosine kinase-1 (sFlt-1) and soluble endoglin (sEng), which circulate systemically and antagonize pro-angiogenic factors like vascular endothelial growth factor (VEGF) and placental growth factor (PlGF). These antiangiogenic factors bind to and neutralize circulating VEGF and PlGF, leading to widespread endothelial cell dysfunction. The endothelial dysfunction manifests as loss of the normal vasodilatory capacity, increased vascular permeability, increased thrombogenicity, and activation of the coagulation cascade. The sFlt-1/PlGF ratio becomes significantly elevated in gestational hypertension and preeclampsia, and can serve as a biomarker of disease severity.

• Activation of the renin-angiotensin-aldosterone system (RAAS) and abnormal nitric oxide metabolism: In normal pregnancy, there is physiologic activation of the RAAS with increased renin, angiotensinogen, and aldosterone levels, yet blood pressure typically decreases due to increased vasodilatory capacity from enhanced nitric oxide (NO) and prostacyclin production. In gestational hypertension, there is heightened sensitivity to angiotensin II despite normal or only moderately elevated RAAS activity, suggesting altered receptor expression or impaired reflex vasodilation. Additionally, endothelial dysfunction leads to decreased production of NO and prostacyclin by the vascular endothelium, reducing vasodilation and allowing unopposed vasoconstriction from angiotensin II, norepinephrine, and other vasoconstrictors. This imbalance between vasoconstrictors and vasodilators perpetuates hypertension throughout pregnancy.

• Oxidative stress and inflammation: The placental ischemia and endothelial dysfunction generate excessive reactive oxygen species (ROS), including superoxide and hydroxyl radicals, which exceed the capacity of antioxidant systems (superoxide dismutase, catalase, glutathione peroxidase). These ROS directly damage endothelial cells, promote lipid peroxidation, and activate inflammatory cascades. Oxidative stress inactivates NO by converting it to peroxynitrite, further reducing vasodilation. Systemically, there is activation of innate immunity with increased levels of inflammatory cytokines (TNF-α, IL-6, IL-8), C-reactive protein, and complement activation, perpetuating a state of chronic systemic inflammation that contributes to vasoconstriction and hypertension.

• Platelet activation and thrombotic tendency: The endothelial dysfunction and oxidative stress promote platelet aggregation and activation, with increased circulating levels of thromboxane A2 (a potent vasoconstrictor and platelet activator) and decreased prostacyclin. This shift in the thromboxane-prostacyclin balance increases thrombotic risk and vasoconstriction. Platelet microparticles accumulate and contribute to further endothelial damage and activation of tissue factor-mediated coagulation, though gestational hypertension typically does not show the severe thrombocytopenia or coagulopathy seen in preeclampsia.

• Maternal predisposing factors and genetic susceptibility: Preexisting conditions such as chronic hypertension, obesity, metabolic syndrome, and polycystic ovary syndrome (PCOS) lower the threshold for developing gestational hypertension by creating a state of baseline endothelial dysfunction, insulin resistance, and chronic inflammation. Genetic polymorphisms in genes encoding components of the RAAS (angiotensinogen, ACE), endothelial NO synthase (eNOS), and other vasoregulatory proteins increase individual susceptibility. Maternal factors such as advanced maternal age (≥35 years), multiparity paradoxically increases risk if there was prior preeclampsia, and African ancestry are associated with increased risk, suggesting genetic and epigenetic contributions to abnormal placentation.

• Advanced maternal age (≥35 years): Women ≥35 years have approximately 2-3 fold increased risk of gestational hypertension compared to women 20-24 years. The mechanism relates to baseline vascular stiffness, endothelial dysfunction, increased oxidative stress, and higher prevalence of comorbidities (obesity, chronic hypertension, diabetes) that predispose to abnormal placentation. Advanced maternal age is consistently associated with both gestational hypertension and its progression to preeclampsia.

• Obesity (BMI ≥30 kg/m²): Obesity is associated with 1.5-3 fold increased risk and is one of the most modifiable risk factors. Obesity creates a proinflammatory state with elevated circulating leptin and decreased adiponectin, both contributing to endothelial dysfunction, insulin resistance, and altered RAAS function. Obese women have increased systemic vascular resistance at baseline and impaired vasodilatory capacity to pregnancy-induced hemodynamic changes.

• Preexisting chronic hypertension or elevated blood pressure: Women with prior diagnosis of chronic hypertension or those with baseline elevated blood pressure (even if not formally diagnosed) are at markedly increased risk. Some women with "masked" hypertension (normal office BP but elevated out-of-office readings) may present with apparent gestational hypertension. The distinction is critical because these women have underlying endothelial dysfunction and vascular disease that worsens during pregnancy.

• Prior history of preeclampsia or gestational hypertension: Women with prior preeclampsia have approximately 25-35% recurrence risk in subsequent pregnancies, with some having recurrence of preeclampsia and others manifesting as gestational hypertension. Similarly, women with prior gestational hypertension in a previous pregnancy have increased risk (approximately 20-30% risk of recurrence). This reflects persistent placental vascular dysfunction and maternal endothelial dysfunction between pregnancies.

• Maternal diabetes mellitus (pregestational or gestational): Both type 1 and type 2 pregestational diabetes significantly increase risk, as diabetic women have baseline microvascular and macrovascular endothelial dysfunction. Additionally, women who develop gestational diabetes mellitus (GDM) during the index pregnancy are at increased risk of developing hypertensive disorders, reflecting shared pathophysiology of insulin resistance and vascular dysfunction.

• Multifetal gestation (twins, higher-order multiples): Women carrying multiples have approximately 2-3 fold increased risk of gestational hypertension compared to singleton pregnancies. The mechanism involves greater placental mass, increased hemodynamic demands, and potentially greater degree of placental hypoperfusion relative to the increased vascular space.

• Polycystic ovary syndrome (PCOS): PCOS is associated with approximately 1.5-2 fold increased risk of gestational hypertension, mediated by insulin resistance, chronic low-grade inflammation, and endothelial dysfunction characteristic of this syndrome. The hyperandrogenism in PCOS may also contribute to vascular dysfunction.

• African ancestry: African American women have higher incidence of gestational hypertension (8-10% vs 6% in other populations) and more severe manifestations. This likely reflects both genetic factors affecting vascular function and RAAS sensitivity, as well as socioeconomic and environmental factors contributing to higher baseline cardiovascular risk.

• Maternal age <20 years: Conversely, very young maternal age is also a risk factor, particularly in settings of socioeconomic deprivation. The mechanism may relate to ongoing vascular remodeling and incomplete cardiovascular maturation.

• Autoimmune and thrombophilic conditions: Women with antiphospholipid syndrome, systemic lupus erythematosus, or inherited thrombophilias (factor V Leiden, prothrombin gene mutation, protein C/S deficiency) have increased risk of gestational hypertension through mechanisms of placental thrombosis, inflammation, and complement activation.

• Asymptomatic hypertension (most common): Approximately 50-75% of women with gestational hypertension are asymptomatic, with hypertension detected only on routine blood pressure screening at prenatal visits. This underscores the critical importance of consistent blood pressure monitoring at every prenatal visit. Women may be surprised by the diagnosis as they feel well and have no subjective symptoms, yet the hypertension carries significant risk for adverse outcomes.

• Headache: Headache occurs in 20-40% of women with gestational hypertension and may be mild to severe. The mechanism involves cerebral vasospasm from increased circulating vasoconstrictors and endothelial dysfunction, as well as increased intracranial pressure. The headache is often described as throbbing, persistent, and may not respond reliably to acetaminophen. The presence of severe headache, especially if accompanied by visual symptoms, raises concern for severe hypertension or progression to preeclampsia with cerebral involvement.

• Visual symptoms: Blurred vision, scotomata (visual field defects), photopsia (flashing lights), and diplopia occur in 10-20% of women and reflect cerebral or retinal vasospasm from endothelial dysfunction. Cortical blindness can occur in severe cases with hypertensive encephalopathy. Visual symptoms are more commonly associated with severe gestational hypertension or progression to preeclampsia and warrant urgent evaluation.

• Epigastric or right upper quadrant pain: This symptom occurs in a minority of women with gestational hypertension (5-10%) but is more common with preeclampsia with severe features. The pain reflects hepatic capsular distension from hepatic congestion and inflammation. Its presence raises concern for severe hypertension or progression to preeclampsia with liver involvement (HELLP syndrome).

• Edema: Peripheral edema (hands, face, lower extremities) occurs in approximately 30-40% of women with gestational hypertension. It is important to note that edema is common in normal pregnancy due to increased capillary hydrostatic pressure and decreased plasma oncotic pressure, so isolated edema without hypertension is not diagnostic of preeclampsia. However, sudden-onset edema or facial edema (rather than dependent edema) is more concerning for preeclampsia.

• Dyspnea: Dyspnea may occur secondary to pulmonary edema from severe hypertension, heart failure, or HELLP syndrome. Its presence indicates severe disease requiring urgent intervention.

• Physical examination findings:
• Blood pressure elevation: By definition, systolic BP ≥140 mmHg and/or diastolic BP ≥90 mmHg on at least two occasions ≥4 hours apart after 20 weeks gestation in a previously normotensive woman. Severe hypertension is defined as systolic ≥160 mmHg or diastolic ≥110 mmHg.
• Absence of proteinuria: On routine dipstick urinalysis, protein should be absent or trace. If significant proteinuria (≥1+ on dipstick, ≥300 mg/24 hours, or protein/creatinine ratio ≥0.3) is present, the diagnosis becomes preeclampsia rather than gestational hypertension.
• Hyperreflexia and clonus: These neurologic signs reflect hyperirritability of the central nervous system from severe hypertension and are more commonly associated with severe hypertension or preeclampsia. Their presence warrants investigation for severe disease.
• Retinopathy findings: Fundoscopic examination may reveal retinal arteriolar narrowing, flame-shaped hemorrhages, cotton-wool spots, or papilledema in severe cases with hypertensive retinopathy or hypertensive encephalopathy.

• Important clinical variants:
• Gestational hypertension presenting in the third trimester: Most cases present after 32 weeks gestation, with earlier-onset hypertension (20-28 weeks) carrying higher risk of progression to preeclampsia.
• Severe gestational hypertension: Defined as systolic BP ≥160 mmHg or diastolic BP ≥110 mmHg, even in the absence of proteinuria or other features of preeclampsia. This requires immediate intervention and closer monitoring.
• Transient hypertension of pregnancy: Some women normalize their blood pressure before delivery or within 12 hours of delivery, representing transient hypertension rather than true gestational hypertension, though this distinction is often only recognized in retrospect.

• Blood pressure criteria: The diagnostic cornerstone is new-onset hypertension (systolic ≥140 mmHg or diastolic ≥90 mmHg) documented on at least two separate occasions ≥4 hours apart (though in practice, same-visit readings 15 minutes apart are acceptable for initial screening) occurring after 20 weeks gestation in a woman with prior normotensive status. Severe hypertension is ≥160/110 mmHg. It is critical that the blood pressure threshold of ≥140/90 represents a change from the patient's baseline; women with chronic hypertension presenting with BP 140-159/90-109 do not have gestational hypertension but rather chronic hypertension in pregnancy. Accurate blood pressure measurement is essential—readings should be obtained in the sitting position with feet on floor, after 5 minutes of rest, using an appropriately sized cuff placed at heart level.

• Absence of proteinuria: A fundamental distinguishing feature of gestational hypertension is the absence of significant proteinuria. Urine dipstick testing should show trace or no protein; if 1+ or greater protein is present (or ≥300 mg/24 hours on 24-hour urine collection, or protein/creatinine ratio ≥0.3 mg/mg), the diagnosis is preeclampsia rather than gestational hypertension. Approximately 80-85% of women with gestational hypertension have no proteinuria; those with proteinuria should be reclassified as having preeclampsia.

• Laboratory evaluation to exclude preeclampsia:
• Platelet count: Should be ≥150,000/μL in gestational hypertension; thrombocytopenia (<150,000/μL) raises concern for HELLP syndrome or preeclampsia with severe features.
• Liver function tests (AST, ALT, LDH): Should be normal or only minimally elevated in gestational hypertension; significant elevation (AST >70-100 IU/L) suggests hepatic involvement from preeclampsia.
• Serum creatinine and urine output: Serum creatinine should remain <1.1 mg/dL; elevation suggests renal involvement from severe hypertension or preeclampsia. Urine output should be adequate; oliguria (<500 mL/24 hours) raises concern for severe disease.
• **Lactate dehydrogen

Immediate stabilization (severe-range BP ≥160/110 mmHg)

• Acute antihypertensive therapy: ACOG (Practice Bulletin 222, Gestational Hypertension and Preeclampsia) treats persistent severe-range blood pressure as a hypertensive emergency requiring therapy within 30–60 minutes to prevent maternal hemorrhagic stroke. First-line agents are IV labetalol, IV hydralazine, or immediate-release oral nifedipine when IV access is not yet available. Titrate to a goal in the 140s/90s — not normotension — because placental perfusion is pressure-dependent and abrupt drops cause fetal heart rate decelerations.
• Seizure prophylaxis: magnesium sulfate IV loading dose followed by infusion for gestational hypertension with severe-range pressures, which ACOG manages as preeclampsia with severe features. Magnesium is an anticonvulsant (NMDA antagonism, cerebral vasodilation), not an antihypertensive.
• Fetal considerations: continuous fetal monitoring; antenatal betamethasone routinely when delivery is anticipated before 34 0/7 weeks. A single late preterm course may be considered at 34 0/7–36 6/7 weeks in steroid-naive patients expected to deliver within 7 days.

Outpatient management (non-severe disease)

• Antihypertensive drugs are generally not indicated: ACOG Practice Bulletin 222 does not recommend antihypertensive therapy for gestational hypertension without severe features; pharmacotherapy is reserved for severe-range pressures. The CHAP-derived treatment threshold of <140/90 mmHg applies to chronic hypertension in pregnancy — CHAP did not enroll patients with gestational hypertension or preeclampsia, and whether that target extends to gestational hypertension remains unsettled and institution-dependent.
• If a drug is used (severe range, or per local protocol): labetalol (combined alpha/beta blockade), extended-release nifedipine (dihydropyridine CCB), or methyldopa (central alpha-2 agonist, weakest efficacy).
• Surveillance is the mainstay: serial BP, weekly-to-twice-weekly labs (platelets, creatinine, transaminases), urine protein assessment, and antenatal fetal testing with growth ultrasounds — reported progression to preeclampsia ranges from roughly 10–50%, highest when hypertension appears before 32–34 weeks.

Definitive management

• Delivery is the only cure — removal of the placenta removes the sFlt-1 source. ACOG recommends delivery at 37 0/7 weeks for gestational hypertension without severe features, and at 34 0/7 weeks (or sooner for maternal/fetal deterioration) when severe features are present. Vaginal delivery is preferred; cesarean is for obstetric indications only.

Contraindicated

• ACE inhibitors, ARBs, and direct renin inhibitors: fetal renal dysgenesis, oligohydramnios, calvarial hypoplasia, limb contractures. Captopril's short half-life makes it useful for rapid titration outside pregnancy — it is still contraindicated here.
• Atenolol: associated with fetal growth restriction.
• Sodium nitroprusside: reserved for refractory crisis given fetal cyanide/thiocyanate accumulation.
• Diuretics are avoided as initial therapy given already-contracted plasma volume.

Maternal complications of the disease

• Progression to preeclampsia/eclampsia (reported in roughly 10–50% of cases, with the highest rates when hypertension appears before 32–34 weeks): worsening antiangiogenic burden produces proteinuria, thrombocytopenia, or transaminitis. Eclampsia — a generalized tonic-clonic seizure from cerebral vasospasm and loss of autoregulation — is an emergency; treat with magnesium sulfate, not phenytoin or benzodiazepines as first line.
• Hemorrhagic stroke: the leading cause of death in severe-range hypertension; loss of cerebral autoregulation at high systolic pressures. Signaled by thunderclap headache, focal deficits, or altered consciousness. Emergency.
• Posterior reversible encephalopathy syndrome (PRES): vasogenic edema of the parieto-occipital white matter; presents with cortical blindness or seizure, with characteristic posterior hyperintensities on MRI.
• HELLP syndrome: microangiopathic hemolysis, elevated transaminases, low platelets from endothelial injury and fibrin deposition. Signaled by RUQ pain, schistocytes, and falling platelets; may culminate in hepatic subcapsular hematoma or rupture. Emergency.
• Pulmonary edema: increased afterload plus capillary leak and low oncotic pressure; dyspnea with hypoxemia. Emergency.
• Placental abruption: decidual vessel disruption — painful vaginal bleeding, tetanic uterus, non-reassuring tracing, possible DIC. Emergency.

Fetal/neonatal complications

• Fetal growth restriction and oligohydramnios: chronic uteroplacental underperfusion; lagging fundal height, abnormal umbilical artery Doppler.
• Iatrogenic preterm birth: from medically indicated delivery — respiratory distress syndrome, IVH.
• Stillbirth: from acute-on-chronic placental insufficiency.

Complications of treatment

• Magnesium toxicity: progressive neuromuscular blockade — loss of deep tendon reflexes first, then respiratory depression, then cardiac arrest. Risk rises with renal impairment. Monitor reflexes, respirations, urine output; antidote is IV calcium gluconate.
• Hydralazine: reflex tachycardia, headache, and maternal hypotension causing fetal bradycardia.
• Labetalol: neonatal bradycardia and hypoglycemia; avoid in asthma and decompensated heart failure.
• Over-aggressive BP lowering: reduced placental perfusion with fetal decelerations.

Long-term

• Future cardiovascular disease: the ACC/AHA primary prevention guideline names a history of preeclampsia (with premature menopause) as a female-specific risk-enhancing factor for atherosclerotic cardiovascular disease. Separately, cohort data show that gestational hypertension itself strongly predicts later chronic hypertension and cardiovascular events, so postpartum BP follow-up and lifestyle counseling are warranted.

• The defining triad of the diagnosis: new hypertension after 20 weeks, no proteinuria, no severe features — and it must resolve by 12 weeks postpartum. If BP is still elevated at 12 weeks, the retrospective diagnosis is chronic hypertension; if it appeared before 20 weeks, it was chronic hypertension all along.
• Single best next step in a new BP of 145/95 at 34 weeks: repeat the measurement and send preeclampsia labs — CBC for platelets, creatinine, AST/ALT, and a urine protein/creatinine ratio. You cannot call it gestational hypertension until preeclampsia is excluded.
• The distractor examiners love: "no proteinuria rules out preeclampsia." False. Preeclampsia can be diagnosed without proteinuria when severe features are present — thrombocytopenia, doubled transaminases, creatinine >1.1 mg/dL, pulmonary edema, or new cerebral/visual symptoms.
• Severe-range BP (≥160/110) changes everything: per ACOG this is managed as preeclampsia with severe features — IV labetalol or hydralazine (or oral immediate-release nifedipine) within 30–60 minutes, plus magnesium sulfate for seizure prophylaxis, and delivery at ≥34 weeks. Conversely, ACOG Practice Bulletin 222 does not recommend antihypertensives for mild-range gestational hypertension; the CHAP <140/90 target belongs to chronic hypertension in pregnancy.
• Timing of delivery is the classic recall item: 37 0/7 weeks for gestational hypertension without severe features; earlier only for severe features or fetal compromise.
• The association tested most: gestational hypertension progresses to preeclampsia in roughly 10–50% of cases depending on the cohort, and earlier onset (before 32–34 weeks) means substantially higher risk — so expectant management always includes serial labs and fetal growth surveillance.
• Prevention pearl: USPSTF and ACOG recommend low-dose aspirin (81 mg daily) started between 12 and 28 weeks — ideally before 16 weeks — for women at high risk of preeclampsia.
• Drug traps: ACE inhibitors and ARBs are absolutely contraindicated (fetal renal dysgenesis, oligohydramnios, skull hypoplasia); atenolol causes growth restriction. If reflexes disappear on magnesium, stop the infusion and give calcium gluconate.
• Don't forget postpartum: hypertension and even eclampsia can first appear after delivery. ACOG advises BP evaluation within 72 hours (in person or by home monitoring) for women with severe hypertension, and no later than 7–10 days postpartum for hypertensive disorders of pregnancy generally.