Hypertension in Pregnancy
- 1 Chronic hypertension
- 2 Preeclampsia
- 3 Postpartum management of hypertension
- Precedes pregnancy.
- High BP before 20th week.
- 90% is essential. 10% is secondary.
- To find underlying cause:
- Urine analysis: to check for blood, protein, glucose, urea, and electrolytes.
- Renal tract ultrasound.
- Sudden increases in BP.
- Cerebral hemorrhage.
- Hypertensive encephalopathy.
- Do not prevent:
- Placental abruption.
- Super-imposed preeclampsia.
- Adverse perinatal outcome.
- Start treatment when:
- Sustained diastolic BP > 105-110 mmHg.
- Systolic BP >= 160 mmHg.
Drugs used during pregnancy
- Labetolol: Beta-adrenoceptor blocker that also blocks alpha-adrenoceptors.
- A-Methyldopa: centrally acting alpha-adrenergic agonist that inhibits vasoconstricting impulses from medulla oblongata.
- Nifedipine: calcium channel blocker.
- Hampers thrombocyte aggregation.
- Improves urine output within 24 hours of postpartum.
- Has the equivalent effect of hydralazine and labetolol.
- Lowers BP and gives a good perinatal outcome.
- Does not increase the side effects when used together with MgSO4.
|Class||Drug||Onset (minutes)||Peak (minutes)||Dosage|
|Arterial dilator||Hydralazine||10-20||60||5-10 mg IV every 15-30 min|
|Calcium channel blocker||Nifedipine||10||60||10-20 mg PO every 30 min|
|Alpha & beta blocker||Labetolol||5||60||20-40-80 mg IV every 10-20 min (300 mg max)|
|Vein & arterial dilator||Sodium nitroprusside||0.5-5||5||0.2-5.0 µg/kgBW/min|
Drugs that should not be used during pregnancy
- Angiotensin-converting-enzyme (ACE) inhibitors.
- Angiotensin receptor blockers.
Gestational hypertension (hypertension during pregnancy) of:
- BP >= 140/90 mmHg on two separate occasions measured at least 4 hours apart.
- Proteinuria > 300 mg in 24 hours of urine collection.
- Arising after the 20th week of gestation in a previously normotensive woman.
- Resolving completely by the 6th postpartum week.
- Failure of the second wave of trophoblast invasion during 16-20 weeks gestation and failure to destroy the muscularis layer of spiral arterioles.
- The continuum theory: exaggerated form of the inflammatory response, occurring in response to relative increase of trophoblastic debris released from a poorly perfused placenta.
- Endothelial dysfunction.
- Multisystem affected.
- Unpredictable course of disease.
- The only treatment is delivery.
- Calcium supplements.
- Low dose aspirin.
- Stress reduction.
- Assessment of fetal and maternal state.
- Fluid balance.
- Management of complications.
- Eclampsia prophylaxis.
- Consider time and mode of delivery.
- Magnesium sulfate (MgSO4):
- Normally only used in obstetric cases.
- Superior to phenytoin for prophylaxis.
- Superior to phenytoin or diazepam in preventing recurrences.
- 2-4 g IV dose followed by 1-2 g/hour IV or 4 g IM/6 hours.
- Side effects: weakness, paralysis, cardiac toxicity.
- Monitor: reflex, respiration, and level of consciousness.
When to induce baby delivery
- If patient has gestational hypertension only, deliver only if >= 37 weeks.
- If patient has severe preeclampsia, deliver only if >= 34 weeks.
- Deliver in < 34 weeks, in case of:
- Uncontrollable BP.
- Lab evidence showing involvement of multiple organs.
- Suspected fetal distress.
- Uncontrolled seizures.
- Symptoms not responsive to therapy.
Consider referral if the resources are limited and conditions of mother / fetus allows
- BP and maternal symptoms are stable.
- Fetal status good.
- Appropriate anti-hypertensive drugs are started.
- MgSO4 given if eligible.
- Discussion with the patient and family.
- MgSO4 and anti-hypertensives can be potentially fatal if overdosed.
Postpartum management of hypertension
- BP usually rises progressively over the first five days after after delivery.
- BP peaks at 3-6 days after delivery.
- 10% of maternal deaths are attributed to postpartum hypertensive disorders.
- Rapid and complete resolution within six weeks of delivery.
- There is risk of cardiovascular disease and renal disease for several years after delivery.