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

2.       Hypertension in pregnancy: Evidence Update May 2012 http://www.nice.org.uk/guidance/cg107/evidence/evidence-updates-134790445