Management and diagnosis of high BP in pregnancy: NICE Guideline

NICE has released its 2019 guidelines on the diagnosis and management of high blood pressure(hypertension) in pregnancy. Hypertensive disorders of pregnancy constitute one of the leading causes of maternal and perinatal mortality worldwide. A woman is considered to have gestational hypertension, or high blood pressure developed in pregnancy, after the first 20 weeks. Prior to that, hypertension is generally deemed to have predated the pregnancy and is considered chronic high blood pressure.

Following are the major recommendations:

1. Reducing the risk of hypertensive disorders in pregnancy

• Advise pregnant women to see a healthcare professional immediately if they experience symptoms of pre-eclampsia.


• Advise pregnant women at high risk of pre-eclampsia to take 75–150 mg of aspirin daily from 12 weeks until the birth of the baby.


• Advise pregnant women with more than 1 moderate risk factor for pre-eclampsia to take 75–150 mg of aspirin daily from 12 weeks until the birth of the baby.


• Advise pregnant women with more than 1 moderate risk factor for pre-eclampsia to take 75–150 mg of aspirin daily from 12 weeks until the birth of the baby.


• Do not use the following to prevent hypertensive disorders during pregnancy: nitric oxide donors, progesterone, diuretics, low molecular weight heparin.


• Do not recommend the following supplements solely with the aim of preventing hypertensive disorders during pregnancy:
  
  
  
  • magnesium
  
  
  • folic acid
  
  
  • antioxidants (vitamins C and E)
  
  
  • fish oils or algal oils
  
  
  • garlic
  
  
  
  


• Do not recommend salt restriction during pregnancy solely to prevent gestational hypertension or pre-eclampsia.


• Give the same advice on rest, exercise and work to women with chronic hypertension or at risk of hypertensive disorders during pregnancy as healthy pregnant women.


• For women with pre-existing diabetes or gestational diabetes, see the NICE guideline on diabetes in pregnancy.

2. Assessment of proteinuria in hypertensive disorders of pregnancy

• Interpret proteinuria measurements for pregnant women in the context of a full clinical review of symptoms, signs and other investigations for pre-eclampsia.


• Use an automated reagent-strip reading device for dipstick screening for proteinuria in pregnant women in secondary care settings.


• If dipstick screening is positive (1+ or more), use albumin: creatinine ratio or protein: creatinine ratio to quantify proteinuria in pregnant women.


• Do not use first-morning urine void to quantify proteinuria in pregnant women.


• Do not routinely use 24‑hour urine collection to quantify proteinuria in pregnant women.


• If using protein: creatinine ratio to quantify proteinuria in pregnant women:
  
  
  
  • use 30 mg/mmol as a threshold for significant proteinuria
  
  
  • if the result is 30 mg/mmol or above and there is still uncertainty about the diagnosis of pre-eclampsia, consider re‑testing on a new sample, alongside the clinical review.
  
  
  
  


• If using albumin: creatinine ratio as an alternative to protein: creatinine ratio to diagnose pre-eclampsia in pregnant women with hypertension:
  
  
  
  • use 8 mg/mmol as a diagnostic threshold
  
  
  • if the result is 8 mg/mmol or above and there is still uncertainty about the diagnosis of pre-eclampsia, consider re‑testing on a new sample, alongside the clinical review.
  
  
  
  

3. Management of chronic hypertension in pregnancy

• Offer women with chronic hypertension referral to a specialist in hypertensive disorders of pregnancy to discuss the risks and benefits of treatment.


• Women who take angiotensin-converting enzyme (ACE) inhibitors or angiotensin II receptor blockers should be advised on the risks involved.


• Stop antihypertensive treatment in women taking ACE inhibitors or ARBs if they become pregnant (preferably within 2 working days of notification of pregnancy) and offer alternatives.


• Advise women who take antihypertensive treatments other than ACE inhibitors, ARBs, thiazide or thiazide-like diuretics that the limited evidence available has not shown an increased risk of congenital malformation with such treatments.


• Offer pregnant women with chronic hypertension advice on weight management, exercise, healthy eating, lowering the amount of salt in their diet.


• Continue with existing antihypertensive treatment if safe in pregnancy, or switch to an alternative treatment.


• When using medicines to treat hypertension in pregnancy, aim for a target blood pressure of 135/85 mmHg.


• Consider labetalol to treat chronic hypertension in pregnant women. Consider nifedipine for women in whom labetalol is not suitable, or methyldopa if both labetalol and nifedipine are not suitable.


• Offer pregnant women with chronic hypertension aspirin 75–150 mg once daily from 12 weeks.


• Offer placental growth factor (PlGF)-based testing to help rule out pre-eclampsia between 20 weeks and up to 35 weeks of pregnancy if women with chronic hypertension are suspected of developing pre-eclampsia.


• If a woman has taken methyldopa to treat chronic hypertension during pregnancy, stop within 2 days after the birth and change to an alternative antihypertensive treatment.

4. Management of gestational hypertension

• In women with gestational hypertension, a full assessment should be carried out in a secondary care setting by a healthcare professional who is trained in the management of hypertensive disorders of pregnancy.


• Offer women with gestational hypertension the tests and treatment listed in table 1.

Table 1 Management of pregnancy with gestational hypertension

• Offer labetalol to treat hypertension in pregnant women with pre-eclampsia. Offer nifedipine for women in whom labetalol is not suitable, and methyldopa if labetalol or nifedipine are not suitable. Base the choice on any pre-existing treatment, side-effect profiles, risks (including fetal effects) and the woman's preference.


• Record maternal and fetal thresholds for planned early birth before 37 weeks in women with pre-eclampsia.


• Involve a senior obstetrician in any decisions on the timing of birth for women with pre-eclampsia

• In women with chronic hypertension, carry out an ultrasound for fetal growth and amniotic fluid volume assessment, and umbilical artery doppler velocimetry at 28 weeks, 32 weeks and 36 weeks.


• In women with chronic hypertension, only carry out cardiotocography if clinically indicated.


• In women with gestational hypertension, carry out an ultrasound for fetal growth and amniotic fluid volume assessment and umbilical artery doppler velocimetry at diagnosis and if normal repeat every 2 to 4 weeks, if clinically indicated.


• In women with gestational hypertension, only carry out cardiotocography if clinically indicated.


• Carry out cardiotocography at diagnosis of pre-eclampsia or severe gestational hypertension.


• In women with pre-eclampsia or severe gestational hypertension, repeat ultrasound for fetal growth and amniotic fluid volume assessment or umbilical artery doppler velocimetry every 2 weeks, with subsequent surveillance and monitoring determined by the findings of these scans.


• Carry out an ultrasound for fetal growth and amniotic fluid volume assessment and umbilical artery doppler velocimetry starting at between 28 and 30 weeks.


• In women who need additional fetal monitoring, carry out cardiotocography only if clinically indicated.

7. Intrapartum care

• Give advice and treatment to women with hypertensive disorders of pregnancy in line with the NICE guideline on intrapartum care, unless there are recommendations in this guideline on the same topic. Offer care in accordance with the NICE guideline on intrapartum care for women with hypertension whether treated or untreated and not just on the basis of blood pressure in labour.


• Determine the need for haematological and biochemical tests during labour in women with hypertension using the same criteria as in the antenatal period even if regional analgesia is being considered.


• Do not preload women who have severe pre-eclampsia with intravenous fluids before establishing low-dose epidural analgesia or combined spinal-epidural analgesia.


• Do not routinely limit the duration of the second stage of labour in women with controlled hypertension.


• Consider operative or assisted birth in the second stage of labour for women with severe hypertension whose hypertension has not responded to initial treatment.

8. Medical management of severe hypertension, severe pre-eclampsia or eclampsia in a critical care setting

• If a woman in a critical care setting who has severe hypertension or severe pre-eclampsia has or previously had an eclamptic fit, give intravenous magnesium sulfate.


• Consider giving intravenous magnesium sulfate to women with severe pre-eclampsia who are in a critical care setting if birth is planned within 24 hours.


• Do not use dexamethasone or betamethasone for the treatment of HELLP syndrome.


• Do not use volume expansion in women with severe pre-eclampsia unless hydralazine is the antenatal antihypertensive.


• In women with severe pre-eclampsia, limit maintenance fluids to 80 ml/hour unless there are other ongoing fluid losses (for example, haemorrhage).


• Choose the mode of birth for women with severe hypertension, severe pre-eclampsia or eclampsia according to the clinical circumstances and the woman's preference.

9. Antihypertensive treatment during the postnatal period, including during breastfeeding

• Advise women with hypertension who wish to breastfeed that their treatment can be adapted to accommodate breastfeeding and that the need to take antihypertensive medication does not prevent them from breastfeeding.


• Offer enalapril to treat hypertension in women during the postnatal period, with appropriate monitoring of maternal renal function and maternal serum potassium.


• When treating women with antihypertensive medication during the postnatal period, use medicines that are taken once daily when possible.


• Where possible, avoid using diuretics or angiotensin receptor blockers to treat hypertension in women in the postnatal period who are breastfeeding or expressing milk.