ASK DIS: Management of Hypertension in Pregnancy

Hypertension in pregnancy defined as a systolic blood pressure (BP) ≥140 mmHg and/or a diastolic BP ≥ 90 mmHg.
An increase of 15 mmHg and 30 mmHg diastolic and systolic BP levels above baseline BP respectively is no longer recognised as hypertension if absolute values are below 140/90 mmHg.
But close observation is warranted, especially if proteinuria and hyperuricaemia are also present

PRECONCEPTION

Atenolol has been shown to lead to fetal growth restriction. The use of ARBs, ACEIs and thiazide diuretics are associated with fetal anomaly and are therefore contraindicated in pregnancy.
The drugs of choice in pregnancy are still methyldopa and labetalol.
Labetalol safety : not know to be harmful except possibly in the first trimester, and breastfeeding infants should be monitored as there is a risk of possible toxicity due to alpha and beta-blockade
Pregnant women with uncomplicated chronic hypertension, target BP is lower than 150/100 mmHg. In the presence of target organ damage secondary to chronic hypertension, the aim is to maintain the BP below 140/90 mmHg.

WOMAN AT RISK OF PRE-ECLAMPSIA

High risk patients should be prescribed aspirin (75mg–100mg daily) from 12 weeks gestation until delivery
Moderate risk patients, aspirin prophylaxis must be commenced before 16 weeks gestation for optimal effectiveness
Low dietary calcium intake (less than 600 mg day), high calcium supplementation of 1.5g/day significantly reduces the risk of eclampsia, severe gestational hypertension, and severe preeclamptic complication index
Combined vitamins C and E (i.e. tocopherol from soybean) should be avoided because they significantly increase the incidence of low birth weight without any preventive effect against preeclampsia.

SEVERE PRE-ECLAMPSIA

Anti-hypertensive treatment should be initiated if diastolic BP is persistently ≥100 mmHg. The target BP to achieve is DBP between 80-100 mmHg.
Diuretics are generally contraindicated as they reduce plasma volume, may cause intrauterine growth restriction (IUGR) and may possibly increase perinatal mortality
In the event of an acute hypertensive crisis IV hydrallazine (2.5-5 mg bolus or infusion)orIV labetalol (10-20 mg slow bolus over 5 minutes or infusion), or Oral nifedipine (10mg stat dose). Sublingual nifedipine is no longer recommended.
High calcium supplementation of 1.5 g/day significantly reduces the risk of eclampsia, severe gestational hypertension and severe preeclamptic complication index in pregnant women with low dietary calcium intake.
Pregnant women who are at high risk of developing preeclampsia should be referred to an obstetrician. Specialist management will include Doppler ultrasonography and aspirin pharmacoprophylaxis.

ECLAMPTIC FIT

Prevention of eclampsia and to abort an eclamptic fit - Parenteral magnesium sulphate. It provides fetal neuroprotection following preterm birth with a significant reduction in the incidence of cerebral palsy
Alternative : IV diazepam, but it is inferior in efficacy compared to magnesium sulphate

POSTPARTUM CARE

Antihypertensives should be tapered down and not stopped suddenly
Preeclampsia Patient – usually need approximately 2 weeks of antihypertensives after postpartum
Gestational Hypertension Patient – usually need approximately 1 week of antihypertensives

REFERENCES

1. Malaysia Clinical Practice Guidelines 2013- Management of Hypertension, 4^TH edition. 2013

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