Hypertension in Pregnancy

Definition | Aetiology | Pathophysiology | Risk Factors | Signs and Symptoms | Investigations | Management | References

Definition

Hypertension in Pregnancy is defined as a blood pressure of 140/90 mmHg or higher during pregnancy. It can be classified into chronic hypertension (pre-existing or diagnosed before 20 weeks of gestation), gestational hypertension (diagnosed after 20 weeks without proteinuria), and pre-eclampsia (gestational hypertension with proteinuria or other organ dysfunction).

Aetiology

The exact cause of hypertension in pregnancy, particularly pre-eclampsia, is not fully understood. However, it is believed to be related to abnormal placental development and poor placental perfusion, leading to endothelial dysfunction and systemic inflammation.

Pathophysiology

Pre-eclampsia is characterised by widespread endothelial dysfunction, resulting in vasoconstriction, increased vascular permeability, and activation of the coagulation cascade. These changes lead to hypertension, proteinuria, and multi-organ involvement, including the liver, kidneys, brain, and placenta.

Risk Factors

• Primiparity (first pregnancy).
• Advanced maternal age (over 35 years).
• Obesity.
• Multiple pregnancies (e.g., twins or triplets).
• Pre-existing conditions such as chronic hypertension, diabetes mellitus, or renal disease.
• Family history of pre-eclampsia.
• Previous history of pre-eclampsia in a prior pregnancy.

Signs and Symptoms

• Hypertension (blood pressure ≥ 140/90 mmHg).
• Proteinuria (≥ 300 mg/24 hours or protein/creatinine ratio ≥ 30 mg/mmol).
• Severe headache.
• Visual disturbances (e.g., blurred vision, flashing lights).
• Epigastric pain or right upper quadrant pain.
• Nausea and vomiting.
• Sudden swelling of the face, hands, or feet.
• Reduced fetal movements.

Investigations

• Blood Pressure Monitoring: Regular monitoring of blood pressure to assess severity.
• Urinalysis: To check for proteinuria, which is a key diagnostic criterion for pre-eclampsia.
• Blood Tests: Full blood count (FBC), liver function tests (LFTs), renal function tests (urea, creatinine), and coagulation profile to assess for complications.
• Fetal Monitoring: Ultrasound to assess fetal growth, amniotic fluid volume, and Doppler studies of the umbilical artery to monitor fetal well-being.

Management

Management of hypertension in pregnancy, particularly pre-eclampsia, depends on the severity of the condition and the gestational age:

• Primary Care Management:
  • Antenatal Monitoring: Regular antenatal visits for blood pressure monitoring and urinalysis.
  • Blood Pressure Control: Antihypertensive medications such as labetalol, methyldopa, or nifedipine may be used to manage blood pressure.
  • Aspirin: Low-dose aspirin (75-150 mg daily) may be prescribed from 12 weeks of gestation until delivery for women at high risk of pre-eclampsia.
  • Referral to Specialist: Women with pre-eclampsia or severe hypertension should be referred to an obstetrician for specialist care.
• Specialist Care:
  • Hospitalisation: Women with severe pre-eclampsia or worsening symptoms may require hospital admission for close monitoring and treatment.
  • Magnesium Sulphate: Used to prevent seizures in women with severe pre-eclampsia or eclampsia.
  • Timing of Delivery: The definitive treatment for pre-eclampsia is delivery of the baby. The timing depends on the severity of the condition and gestational age. In severe cases, early delivery may be necessary, even if preterm.
  • Corticosteroids: Administered to enhance fetal lung maturity if early delivery is anticipated before 34 weeks of gestation.

References

1. NHS (2024) Pre-eclampsia. Available at: https://www.nhs.uk/conditions/pre-eclampsia/ (Accessed: 24 June 2024).
2. National Institute for Health and Care Excellence (2024) Hypertension in Pregnancy: Diagnosis and Management. Available at: https://www.nice.org.uk/guidance/ng133 (Accessed: 24 June 2024).
3. Royal College of Obstetricians and Gynaecologists (2024) Management of Hypertensive Disorders during Pregnancy. Available at: https://www.rcog.org.uk/en/guidelines-research-services/guidelines/gtg107/ (Accessed: 24 June 2024).
4. British Medical Journal (2024) Hypertension in Pregnancy. Available at: https://www.bmj.com/content/350/bmj.h3735 (Accessed: 24 June 2024).

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