Gestational Hypertension and Hypertensive Disorders of Pregnancy

Overview

Hypertensive disorders of pregnancy (HDP) encompass a group of conditions characterized by high blood pressure during pregnancy, which can pose significant risks to both the mother and the fetus. These disorders include chronic hypertension, gestational hypertension, preeclampsia, and eclampsia. They are among the leading causes of maternal and perinatal morbidity and mortality worldwide, affecting approximately 5-10% of pregnancies. In Sri Lanka, HDP affect nearly 10% of pregnant women and are a major contributor to direct maternal deaths, ranking as the second leading cause in recent years. Gestational hypertension specifically refers to new-onset high blood pressure after 20 weeks of gestation without proteinuria or other organ involvement, while preeclampsia and eclampsia represent more severe forms.

HDP can lead to complications such as preterm birth, low birth weight, placental abruption, and long-term cardiovascular risks for the mother. Early detection and management are crucial, with guidelines from organizations like the American College of Obstetricians and Gynecologists (ACOG), World Health Organization (WHO), and the Sri Lanka College of Obstetricians & Gynaecologists (SLCOG) emphasizing regular monitoring and timely intervention.

Classification

Hypertensive disorders of pregnancy are classified into several categories based on timing, severity, and associated features:

• Chronic Hypertension: High blood pressure (≥140/90 mm Hg) present before pregnancy or before 20 weeks of gestation, or persisting beyond 12 weeks postpartum.

• Gestational Hypertension: New-onset hypertension (≥140/90 mm Hg) after 20 weeks of gestation without proteinuria or end-organ damage. It resolves by 12 weeks postpartum in most cases.

• Preeclampsia: Gestational hypertension accompanied by proteinuria (≥300 mg in 24 hours) or evidence of end-organ dysfunction, such as thrombocytopenia, renal insufficiency, impaired liver function, pulmonary edema, or cerebral/visual symptoms. It can occur with or without severe features.

• Preeclampsia with Severe Features: Includes blood pressure ≥160/110 mm Hg, severe headaches, visual disturbances, epigastric pain, or laboratory abnormalities like elevated liver enzymes or low platelets.

• Eclampsia: The onset of seizures in a woman with preeclampsia, unrelated to other causes. It is a medical emergency.

• HELLP Syndrome: A variant of preeclampsia involving Hemolysis, Elevated Liver enzymes, and Low Platelet count.

Superimposed preeclampsia occurs when preeclampsia develops in a woman with chronic hypertension.

Signs and Symptoms

Many women with HDP are asymptomatic, especially in early stages, making routine screening essential. Common signs and symptoms include:

• Elevated blood pressure (≥140/90 mm Hg on two occasions at least 4 hours apart).

• Proteinuria (protein in urine), detected via dipstick or 24-hour collection.

• Swelling (edema) in the face, hands, or legs, though this can be normal in pregnancy.

For preeclampsia/eclampsia:

• Severe headaches, visual changes (blurred vision, spots), epigastric or right upper quadrant pain.

• Shortness of breath, nausea, vomiting.

• Seizures in eclampsia.

Fetal signs may include growth restriction or reduced amniotic fluid.

Causes and Pathophysiology

The exact cause of HDP is unknown, but it is believed to involve abnormal placental development leading to reduced blood flow, endothelial dysfunction, and systemic inflammation. Factors include poor trophoblast invasion, oxidative stress, and immune maladaptation. In preeclampsia, this results in widespread vascular changes, organ damage, and release of anti-angiogenic factors like sFlt-1.

Risk Factors

Risk factors for HDP include:

• First pregnancy, advanced maternal age (>35), obesity, multiple gestation.

• Pre-existing conditions: Chronic hypertension, diabetes, kidney disease, autoimmune disorders (e.g., lupus).

• Family history of preeclampsia, previous HDP.

In Sri Lanka and South Asia, additional factors like rheumatic heart disease and nutritional deficiencies may exacerbate risks, with women who had HDP facing a 3-4 fold increased risk of future cardiovascular disease.

Diagnosis

Diagnosis involves:

• Blood pressure measurement: ≥140/90 mm Hg on two readings.

• Urine tests: Protein/creatinine ratio ≥0.3 or 24-hour protein ≥300 mg.

• Blood tests: For liver enzymes, platelets, creatinine to assess organ function.

• Fetal monitoring: Ultrasound for growth, Doppler for blood flow.

In Sri Lanka, SLCOG guidelines recommend routine antenatal BP checks and referral to tertiary care for severe cases.

Treatment

Management focuses on maternal stabilization and timely delivery:

• Mild Gestational Hypertension: Close monitoring, lifestyle advice (rest, diet), no routine antihypertensives unless BP ≥150/100 mm Hg.

• Preeclampsia: Hospitalization for monitoring. Antihypertensives (e.g., labetalol, nifedipine) for BP ≥160/110 mm Hg. Magnesium sulfate for seizure prevention in severe cases.

• Eclampsia: Immediate magnesium sulfate, antihypertensives, and delivery.

Delivery is the definitive treatment, often induced after 37 weeks for mild cases or earlier if severe. In Sri Lanka, guidelines include calcium supplementation (1g daily) and specific drugs like hydralazine for emergencies.

Prevention

• Low-dose aspirin (81-150 mg daily) starting at 12-16 weeks for high-risk women reduces preeclampsia risk by 10-20%.

• Calcium supplementation in low-intake populations.

• Lifestyle: Healthy weight, diet, exercise before and during pregnancy.

In Sri Lanka, antenatal care includes risk assessment and education on symptoms.

Prognosis

Most women recover fully postpartum, but HDP increases future risks of hypertension, cardiovascular disease, and recurrent HDP (up to 20% in subsequent pregnancies). In Sri Lanka, women with HDP history have a 3.3-fold higher risk of hypertension and 2.75-fold for metabolic syndrome. Fetal outcomes improve with early intervention, but preterm delivery remains a concern.

Epidemiology

Globally, preeclampsia affects 2-8% of pregnancies, with eclampsia in 1.4% of deliveries. In South Asia, including Sri Lanka, prevalence is around 9-10%, contributing to 9-26% of maternal deaths. Sri Lanka's strong antenatal system has reduced mortality, but HDP remains a priority.

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