Referral to secondary care

• Expert opinion from the National Institute for Health and Clinical Excellence (NICE) is that all pregnant women with any degree of new-onset hypertension require a full assessment in secondary care by a healthcare professional who is trained in the management of hypertensive disorders [National Collaborating Centre for Women's and Children's Health, 2010].

Monitoring and review

• NICE found [National Collaborating Centre for Women's and Children's Health, 2010]:
• No studies that provided evidence on the frequency of blood pressure measurements. It recommends that the frequency of monitoring will be determined by the degree of hypertension and may be influenced by medical history and the presence of risk factors.
• The evidence regarding the gestational age at diagnosis and the subsequent development of severe pre-eclampsia or fetal growth restriction difficult to interpret. NICE agreed that the development of gestational hypertension before 35 weeks deserves special consideration and monitoring.
• Only poor-quality evidence about the role of haematological and biochemical blood tests. NICE suggests the limited use of the recommended blood tests to help to rule out disease progression.

Drug treatment of gestational hypertension

• NICE studied the Cochrane systematic review [Abalos et al, 2007] on the use of antihypertensive therapy for mild to moderate hypertension in pregnancy [National Collaborating Centre for Women's and Children's Health, 2010]. Realizing that this review did not specifically address the treatment of women with gestational hypertension, NICE looked at all of the individual studies. In many of the studies either the population investigated was not clearly defined or it included a mixed population. NICE concluded that:
• There is limited good-quality evidence about treatment for gestational hypertension. This evidence does not support blood pressure-lowering treatment for mild or moderate gestational hypertension with the aim of improving pregnancy outcomes, but it does support starting treatment once severe hypertension has developed.
• There is not enough evidence to know whether antihypertensive treatment prevents rare serious events, such as a stroke or placental abruption.
• There is insufficient evidence about the target blood pressure; it must be low enough to prevent secondary damage, such as stroke, without being excessively low and thereby potentially affecting fetal growth.
• There is good evidence to show that beta-blockers and labetalol reduce the risk of severe hypertension. One small, poor-quality, quasi-randomized trial found a statistically significant reduction in the risk of pre-eclampsia/proteinuria with labetalol compared with methyldopa. However, proteinuria was not defined.
• There was little evidence regarding calcium-channel blockers.
• NICE reached a consensus that the association between beta-blockers and reduced fetal growth was likely to be the result of excessive lowering of blood pressure and related to the dose.
• Taking the above into account, NICE recommends that:
• Labetalol should be used first line as it seems to be as effective and safe as other antihypertensive drugs and it is licensed for use in pregnancy.
• Alternative treatment including methyldopa and nifedipine should be offered after considering adverse effect profiles for the woman, fetus, and newborn baby. NICE recommends using these treatments in women of Afro–Caribbean origin as it is not known if this group of women responds well to beta-blockers in pregnancy (a poor response to beta-blockers has been recognized in people of Afro–Caribbean origin who are not pregnant).

Timing of the birth

• NICE reviewed the evidence from a large, open-label, randomized controlled trial (RCT) done in the Netherlands [National Collaborating Centre for Women's and Children's Health, 2010]. Although NICE concluded that because of different clinical practice the results are not directly applicable to the UK, their expert view was that if gestational hypertension becomes severe (160/110 mmHg or greater) even though the women is being treated with antihypertensive drugs, then the woman should be offered immediate birth after a course of antenatal steroids.

Bed rest

• NICE recommends that bed rest in hospital should not be offered as a treatment for gestational hypertension. NICE reviewed the evidence in relation to bed rest in an RCT carried out on 218 women in Zimbabwe. This study examined the effectiveness of hospital bed rest compared with normal activities at home on the risk of severe hypertension in women with chronic hypertension or gestational hypertension [National Collaborating Centre for Women's and Children's Health, 2010].
• There were 185 women in the gestational hypertension group who were randomized to normal activities at home (90 women) or hospital bed rest (95 women).
• Although the study found that hospital bed rest was more effective than continuing normal activities at home (OR 0.52, 95% CI 0.27 to 0.99), NICE pointed out that that the study was small and also conducted in a healthcare setting which was not applicable to the UK. NICE were also concerned that prolonged bed rest may increase the risk of venous thromboembolism.

Use of aspirin in women with gestational hypertension

• NICE reviewed the evidence from [National Collaborating Centre for Women's and Children's Health, 2010]:
• A Cochrane systematic review that reported a 40% reduction in the relative risk of progressing to pre-eclampsia in women with gestational hypertension taking aspirin compared with placebo or no treatment.
• A small RCT that found no statistically significant difference for progression to moderate or severe pre-eclampsia between 23 women who were randomized to take 100 mg of aspirin a day and 24 women who received a placebo.
• Considering the above, NICE did not consider the evidence sufficient to support the use of aspirin in women with gestational hypertension unless they have additional risk factors for pre-eclampsia.