Hypertension in Pregnancy- Classification, Risk factors, Short-term and long-term management

April 19, 2020 Rima Medical Science 0

Definition and Epidemiology

  • Elevation of BP ≥140 mm Hg systolic and/or ≥90 mm Hg diastolic.
  • Complicates 5-10% of pregnancies. It is one of the members of the deadly triad in pregnancy along with hemorrhage and infection.

Classification

  • Gestational Hypertension
  • Preeclampsia and eclampsia syndrome
  • Chronic hypertension
  • Preeclampsia superimposed on Chronic Hypertension

1. Gestational Hypertension

  • BP of 140/90 mmHg systolic or greater for the first time after midpregnancy, without proteinuria.
  • Almost half of the patients subsequently develop preeclampsia syndrome with headache, epigastric pain, proteinuria and thrombocytopenia.
  • Resolves by 12 weeks postpartum.

2. Preeclampsia and eclampsia syndrome

  • Preeclampsia is new onset of hypertension with proteinuria (an excess of protein in urine) after 20 weeks gestation.
  • Systolic blood pressure ≥140 mm Hg, diastolic pressure ≥90 mm Hg or both.
  • Proteinuria of 0.3 g or greater in a 24-hour urine specimen.
  • It is of two categories; Mild Preeclampsia and Severe Preeclampsia.
  • Eclampsia is occurrence of generalized convulsion and/or coma in the setting of preeclampsia, with no other neurological condition.

3. Chronic Hypertension

  • Pre-existing hypertension
  • Systolic pressure≥ 140 mm Hg, diastolic pressure≥ 90 mm Hg or both.
  • Present before 20th week of pregnancy or persists longer than 12 weeks postpartum.

4. Preeclampsia superimposed on Chronic Hypertension

  • Affects 10-25 % of patients with chronic hypertension
  • Preexisting hypertension with the following additional signs/symptoms;

-New onset proteinuria.

– Hypertension and proteinuria beginning prior to 20 weeks of gestation.

– A sudden increase in blood pressure.

– Thrombocytopenia.

– Elevated aminotransferases.

Risk Factors for Hypertension in Pregnancy

  • Nulliparity (the condition in a woman of never having given birth).
  • Preeclampsia in previous pregnancy.
  • Age > 40 years or < 18 years at the time of pregnancy.
  • Family history of pregnancy induced hypertension.
  • Chronic hypertension.
  • Chronic renal disease.
  • Vascular or connective tissue disease.
  • High body mass index.
  • Multifetal gestation.
  • Diabetes mellitus (pregestational and gestational).
  • Hydrops fetalis (serious fetal condition characterized by abnormal accumulation of fluid in two or more fetal compartments).
  • Antiphospholipid antibody syndrome or inherited thrombophilia.
  • Unexplained fetal growth restriction.

Evaluation of hypertension in pregnancy

Diagnosis should be done by laboratory tests.

  • CBC (Complete Blood Count).
  • Renal function test.
  • Liver function test (AST- Aspartate Aminotransferase, ALP- Alkaline Phosphatase, ALT- Alanine Aminotransferase, LD- Lactate Dehydrogenase)
  • Coagulation (PT- Prothrombin Time, PTT- Partial Thromboplastin Time, INR- International Normalised Ratio, Fibrinogen)
  • Urine protein test (Dipstick, 24 hour)

Prevention

  • Dietary manipulation with low salt-diet, calcium or fish oil supplementation.
  • Regular exercise, physical activity or stretching.
  • Use of antioxidants like ascorbic acid (vitamin C), vitamin E, vitamin D.

Management of Hypertension in Pregnancy

  • Depends on severity of hypertension

-Restricted activity

– Closed maternal and fetal monitoring including BP monitoring, fetal growth and well being (NST- Non-Stress Test and U/S- Ultrasound), routine weekly or biweekly blood work.

Short-term Control

  • Hydralazine– IV or oral route. It is direct vasodilator. Have side effects like headache, palpitations, systemic- lupus erythematous like syndrome.
  • Labeatolol– IV or oral route. It is non-selective β1 and α1 blocker. Side effects like headache and tremor are seen.

Long-term control

  • Methyldopa– Oral route. It is α-2 agonist and acts as false neurotransmitter. Side effects like drowsiness, postural hypotension and fluid retention may occur.
  • Nifedipine– Oral route. It is calcium channel blocker. Common side effects are edema and dizziness.

Contraindicated antihypertensive drugs

  • ACE inhibitors like captopril including ramipril and perindopril.
  • ARBs or Angiotensin Receptor Blockers including telmisartan, valsartan, losartan.

Proceed with delivery

  • Vaginal delivery VS Cesarean section.
  • Depends on severity of hypertension.
  • May need to administer antenatal corticosteroids depending on gestation.
  • ONLY CURE IS DELIEVRY.

References

  1. William Obstetrics, 24th edition.
  2. Pharmacology and Pharmacotherapeutics.
  3. A Textbook of Clinical Pharmacology and Therapeutics.
  4. Goodman and Gillman’s Manual of Pharmacology.
  5. https://doi.org/10.1161/01.HYP.37.2.232.