NICE published guidance in 2010 on the management of hypertension in pregnancy. They also made recommendations on reducing the risk of hypertensive disorders developing in the first place. Women who are at high risk of developing pre-eclampsia should take aspirin 75mg od from 12 weeks until the birth of the baby. High risk groups include:

• hypertensive disease during previous pregnancies
• chronic kidney disease
• autoimmune disorders such as SLE or antiphospholipid syndrome
• type 1 or 2 diabetes mellitus

The classification of hypertension in pregnancy is complicated and varies. Remember, in normal pregnancy:

• blood pressure usually falls in the first trimester (particularly the diastolic), and continues to fall until 20-24 weeks
• after this time the blood pressure usually increases to pre-pregnancy levels by term

Hypertension in pregnancy in usually defined as:

• systolic > 140 mmHg or diastolic > 90 mmHg
• or an increase above booking readings of > 30 mmHg systolic or > 15 mmHg diastolic

After establishing that the patient is hypertensive they should be categorised into one of the following groups

Pre-existing HTN:

• A history of hypertension before pregnancy or an elevated blood pressure > 140/90 mmHg before 20 weeks gestation
• No proteinuria, no oedema
• Occurs in 3-5% of pregnancies and is more common in older women

Pregnancy induced HTN:

• Hypertension (as defined above) occurring in the second half of pregnancy (i.e. after 20 weeks)