E. Pre-existing hypertension – Explanation
This lady has pre-existing hypertension. Pregnancy related blood pressure problems (such as
pregnancyinduced hypertension or pre-eclampsia) do not occur before 20 weeks. The raised
ambulatory blood pressure readings exclude a diagnosis of white-coat hypertension.
Note the use of the term ‘pre-existing hypertension’ rather than essential hypertension. Raised blood
pressure in a 36-year-old femaleis not that common and raises the possibility of secondary
hypertension.
Hypertension in pregnancy
The classification of hypertension in pregnancy is complicated and varies. Remember, in normal
pregnancy:
xblood pressure usually falls in the first trimester (particularly the diastolic), and continues to fall until
20-24 weeks
xafter this time the blood pressure usually increases to pre-pregnancy levels by term
Hypertension in pregnancy in usually defined as:
xsystolic > 140 mmHg or diastolic > 90 mmHg
xor 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 hypertension | Pregnancy-induced hypertension (PIH, also known as gestational hypertension) |
Pre-eclampsia |
| A history of hypertension before pregnancy or an elevated blood pressure > 140/90 mmHg before 20 weeks gestationNo proteinuria, no oedemaOccurs in 3-5% of pregnancies and is more common in older women |
Hypertension (as defined above) occurring in the second half of pregnancy (i.e. after 20 weeks)No proteinuria, no oedemaOccurs in around 5-7% of pregnanciesResolves following birth (typically after one month). Women with PIH are at increased risk of future preeclampsia or hypertension later in life |
Pregnancy-induced hypertension in association with proteinuria (> 0.3g / 24 hours)Oedema may occur but is now less commonly used as a criteriaOccurs in around 5% of pregnancies |
