Classification and Management of Hypertensive Disorders in Pregnancy

Definition and Classification

• The International Society for the Study of Hypertension in Pregnancy (ISSHP) classifies hypertensive disorders in pregnancy into hypertension known before pregnancy or present in the first 20 weeks and hypertension arising de novo at or after 20 weeks 1, 2
• Chronic hypertension can be essential or secondary, according to the ISSHP classification 1
• White-coat hypertension is defined as elevated clinic blood pressure but normal home or ambulatory blood pressure, as stated by the ISSHP 1, 3
• Masked hypertension is characterized by normal clinic blood pressure but elevated blood pressure at other times, as defined by the ISSHP 1, 4

Diagnostic Criteria

• Hypertension is defined as systolic blood pressure ≥140 mmHg and/or diastolic blood pressure ≥90 mmHg, according to the ISSHP 1, 4
• Severe hypertension is defined as systolic blood pressure ≥160 mmHg and/or diastolic blood pressure ≥110 mmHg, as stated by the ISSHP 4
• Confirmation of severe hypertension requires confirmation within 15 minutes, while less severe hypertension requires repeated readings over several hours, as recommended by the ISSHP 4

Preeclampsia Diagnosis

• Preeclampsia is diagnosed when gestational hypertension is accompanied by ≥1 new-onset conditions, including proteinuria, renal insufficiency, liver involvement, neurological complications, hematological complications, or uteroplacental dysfunction, at or after 20 weeks' gestation, as defined by the ISSHP 5

Clinical Notes

• The ISSHP recommends that preeclampsia be described as with or without severe features, rather than using the term "severe preeclampsia" 1, 6
• Transient gestational hypertension carries a 40% risk of developing gestational hypertension or preeclampsia later in pregnancy, as reported by the ISSHP 1, 3
• Women with hypertension at or after 20 weeks with unknown earlier blood pressure should be managed as if they have gestational hypertension or preeclampsia, according to the ISSHP 2, 7

Monitoring and Management

• The ISSHP recommends that all women with chronic hypertension have baseline tests to help detect superimposed preeclampsia later in pregnancy, including complete blood count, liver enzymes, renal function, uric acid, and proteinuria assessment 5
• Women with transient gestational hypertension should receive extra monitoring throughout pregnancy, ideally including home blood pressure measurements, as recommended by the ISSHP 5

Classification and Management of Hypertensive Disorders in Pregnancy

Definition and Classification

• The International Society for the Study of Hypertension in Pregnancy (ISSHP) provides a classification system that divides hypertensive disorders into two main temporal categories: hypertension present before or in early pregnancy, and hypertension arising de novo at or after 20 weeks' gestation 8, 9
• Essential hypertension is the most common form of chronic hypertension, typically accompanied by family history and often associated with overweight or obesity 10
• Secondary hypertension includes less common causes such as primary renal parenchymal disorders, fibromuscular hyperplasia of renal arteries, or primary hyperaldosteronism 10

Diagnostic Thresholds and Confirmation

• The ISSHP explicitly recommends against using the term "severe preeclampsia" in clinical practice, instead describing preeclampsia as "with or without severe features" 9
• For less severe hypertension, confirmation requires repeated readings over several hours on the same visit or on two consecutive antenatal visits 10

Ambulatory and Home BP Monitoring

• Normal 24-hour ambulatory BP values before 22 weeks should be below 126/76 mmHg, with awake average below 132/79 mmHg and sleep average below 114/66 mmHg 10
• Approximately 25% of automated home devices differ from standard sphygmomanometry, requiring validation against calibrated devices before clinical use 10

Baseline Testing for Chronic Hypertension

• All women with chronic hypertension require baseline testing at first diagnosis to facilitate later detection of superimposed preeclampsia, including complete blood count, liver enzymes, serum creatinine, electrolytes, and uric acid, as well as urinalysis with microscopy and protein-to-creatinine ratio or albumin-to-creatinine ratio 10

Long-Term Implications

• Women with any hypertensive disorder of pregnancy face significant long-term cardiovascular risks, and annual medical review is advised lifelong, with goals including achieving prepregnancy weight by 12 months postpartum and maintaining healthy lifestyle through exercise and optimal body weight 8, 11

Management of Hypertensive Disorders in Pregnancy

Classification

• Hypertensive disorders in pregnancy are divided into two temporal categories: (1) hypertension present before conception or before 20 weeks’ gestation, and (2) hypertension that first appears at ≥ 20 weeks’ gestation. 12
• Within the early‑onset group, chronic hypertension (essential or secondary) is recognized. 12
• Among hypertension that begins at ≥ 20 weeks, three entities are distinguished: (a) transient gestational hypertension that normalizes with repeated same‑day measurements, (b) persistent gestational hypertension without pre‑eclampsia features, and (c) pre‑eclampsia, which may be de novo or superimposed on chronic hypertension. 12

Monitoring and Risk Assessment

• Women with transient gestational hypertension should receive intensified surveillance throughout pregnancy because they have an approximately 40 % chance of progressing to true gestational hypertension or pre‑eclampsia. 12

Pharmacologic Prevention and Treatment

• Magnesium sulfate is recommended for seizure prophylaxis in patients with eclampsia and in severe pre‑eclampsia (i.e., pre‑eclampsia with severe features). 12
• Evidence regarding the benefit of magnesium sulfate for non‑severe pre‑eclampsia is limited, and consensus is lacking. 12
• Calcium supplementation should be provided to pregnant women with low dietary calcium intake. 12
• Oxytocin is advised for use in the third stage of labor to promote uterine contraction. 12

Timing of Delivery

• For pre‑eclampsia at term (≥ 37 weeks gestation), delivery is recommended. 12
• In pre‑term pre‑eclampsia, clinicians must balance the maternal‑fetal risks of immediate delivery of an immature fetus against the hazards of ongoing disease; individualized decision‑making is essential. 12

Antenatal Corticosteroids

• When pre‑term pre‑eclampsia is likely to require delivery within the next 7 days and gestational age is < 34 weeks, a course of antenatal corticosteroids should be administered to accelerate fetal lung maturation. 12

Areas of Uncertainty

• There is limited consensus on the optimal timing of delivery for women with chronic hypertension, gestational hypertension, or pre‑term pre‑eclampsia, underscoring the need for personalized risk assessment. 12

Management of Headache and Hypertension in Late Second‑Trimester Pregnancy

Diagnosis and Risk Assessment

• Preeclampsia should be considered the primary diagnosis in any pregnant woman ≥20 weeks gestation who presents with headache and hypertension, because this combination signals a high risk of progression to eclampsia and serious maternal morbidity. 13, 14
• Preeclampsia is defined by new‑onset gestational hypertension (BP ≥ 140/90 mmHg) after 20 weeks gestation together with any new maternal organ dysfunction, including neurological symptoms such as headache. 13, 14
• Proteinuria is present in only about 75 % of preeclampsia cases and is not required for the diagnosis; its absence does not exclude the condition. 13, 14
• In the presence of hypertension, headache is an independent risk factor for eclamptic seizures and therefore mandates immediate evaluation. 13, 15
• New‑onset gestational hypertension before 34 weeks gestation carries the highest risk of progression to preeclampsia. 16

Severe Features Requiring Immediate Action

Immediate Diagnostic Workup

• Laboratory panel – complete blood count (including platelet count), liver enzymes (AST, ALT, LDH) and coagulation profile, serum creatinine, electrolytes, uric acid, and quantitative protein assessment (protein‑to‑creatinine or albumin‑to‑creatinine ratio). 13, 17, 14
• Blood pressure verification – repeat measurement within 15 minutes if the initial reading is ≥160/110 mmHg. 16
• Focused clinical assessment – screen for visual changes, epigastric/RUQ pain, hyperreflexia with clonus, and obtain a fetal heart‑rate tracing. 13, 16, 15

Management Thresholds and Hospital Admission

• Admission criteria – any of the following mandates immediate hospitalisation:
  16, 15, 13

• Antihypertensive therapy – initiate within 30–60 minutes when BP ≥ 160/110 mmHg. 16

• Seizure prophylaxis – administer magnesium sulfate for preeclampsia with severe hypertension or with neurological symptoms (headache, visual changes). 16

Clinical Pitfalls to Avoid

• Do not wait for proteinuria to confirm preeclampsia; it is absent in roughly 25 % of cases. 13, 14
• Do not dismiss headache as benign in a hypertensive pregnant patient; it must be managed as preeclampsia until excluded. 13, 14
• Recognise that one‑third of eclamptic seizures occur with diastolic BP ≤ 100 mmHg, so severe hypertension may be absent. 15
• Do not delay antihypertensive treatment while awaiting laboratory results; severe hypertension alone warrants immediate therapy. 16

Guideline Recommendations for Laboratory Evaluation and Management of Severe Hypertension at 36 Weeks Gestation

Essential Laboratory Panel

• Order a complete blood count with platelet count, a comprehensive metabolic panel (including AST, ALT, LDH), serum creatinine, serum uric acid, and a quantitative protein‑to‑creatinine or albumin‑to‑creatinine ratio immediately in any pregnant patient at 36 weeks with severe hypertension. [18][19]

• Define severe hypertension as systolic ≥ 160 mmHg or diastolic ≥ 110 mmHg; this threshold triggers urgent evaluation for preeclampsia and HELLP syndrome. 18

• Platelet count < 100 000/µL constitutes the thrombocytopenia component of HELLP syndrome. [18][19]

• AST or ALT > 2 × the upper limit of normal identifies the liver‑enzyme component of HELLP and often appears before platelet decline. 18

• Serum creatinine (with electrolytes) is used to detect renal insufficiency, a diagnostic criterion for preeclampsia. [18][19]

• Serum uric acid serves as a prognostic marker of disease severity in preeclampsia/HELLP and should be measured as part of baseline assessment. [18][19]

• Hematocrit and peripheral blood smear are required to evaluate hemolysis, the “H” in HELLP syndrome. [18][19]

• Quantitative proteinuria is assessed by spot urine protein‑to‑creatinine or albumin‑to‑creatinine ratio; a ratio ≥ 30 mg/mmol (≈ 265 mg/g) indicates clinically significant proteinuria. [18][19]

Clinical Context at 36 Weeks

• At 36 weeks gestation with severe‑range blood pressure, clinicians must differentiate preeclampsia with severe features from HELLP syndrome; both conditions warrant prompt delivery after maternal stabilization. [20][21]

• Confirmation of severe hypertension (≥ 160/110 mmHg) must be obtained within 15 minutes; laboratory workup should not be delayed while repeating blood pressure measurements. 18

Management Decisions Based on Laboratory Results

• HELLP syndrome confirmed (presence of hemolysis, elevated liver enzymes, and platelets < 100 000/µL) → plan for immediate delivery once coagulopathy and severe hypertension are corrected. [20][21]

• Magnesium sulfate should be initiated for seizure prophylaxis when severe hypertension or neurological symptoms are present. [20][21]

• Betamethasone may be administered to enhance fetal lung maturity if delivery is anticipated, although its benefit is less critical at 36 weeks compared with earlier gestations. [20][21]