Hypertension in pregnancy: diagnosis and management

Context

Hypertensive disorders during pregnancy affect around 8% to 10% of all pregnant women and can be associated with substantial complications for the woman and the baby. Women can have hypertension before pregnancy or it can be diagnosed in the first 20 weeks (known as chronic hypertension), new onset of hypertension occurring in the second half of pregnancy (gestational hypertension) or new hypertension with features of multi-organ involvement (pre-eclampsia).

Although the proportion of women with pregnancy hypertensive disorders overall appears to have stayed reasonably stable, maternal mortality from hypertensive causes has fallen dramatically: less than 1 woman in every million who gives birth now dies from pre-eclampsia. There is consensus that introduction of the 2010 NICE evidence-based guidelines, together with the findings from the confidential enquiry into maternal deaths, has made a pivotal contribution to this fall in maternal mortality. However, hypertension in pregnancy continues to cause substantial maternal morbidity, stillbirths and neonatal deaths, and perinatal morbidity. Women with hypertension in pregnancy are also at increased risk of cardiovascular disease later in life.

Variations in care contribute to inequity in adverse outcomes. Adoption and implementation of evidence-based national guidelines have a central role in reducing this variance and improving care and outcomes across the maternity service. Research that has been done since publication of the previous guideline has addressed areas of uncertainty and highlighted where the recommendations can be updated. A surveillance report from 2017 identified new studies in the following areas:

The scope of this update was limited to these sections; it did not include other areas being looked at by other groups (for example, screening strategies for pre-eclampsia, which is being evaluated by the UK National Screening Committee), and did not look into alternative approaches to categorisation of hypertension in pregnancy (for example, looking at treatment for all types of pregnancy hypertension together, rather than within the subdivisions of chronic hypertension, gestational hypertension and pre-eclampsia). This update has also clarified the basis for the current definition of pre-eclampsia, in order to better align with the stated aims of the 2010 guideline to be consistent with those agreed by the International Society for the Study of Hypertension in Pregnancy (ISSHP).

The aim of the 2019 guideline is to present updated evidence-based recommendations, relevant to practising clinicians, while identifying outstanding areas of uncertainty that need further research. There is a strong argument for uptake of these new guidelines into clinical practice, in order to minimise unnecessary variance and provide optimal care for women and their babies. In doing this, low rates of maternal mortality should be maintained, and progress on reduction of maternal morbidity and perinatal morbidity and mortality can be pursued.