Pre-eclampsia & High Blood Pressure

Blood pressure problems are one of the most common reasons women are admitted to the hospital antenatal ward. The amount of attention received by a woman with 'blood pressure' depends very much upon what kind of disease causes it and how high the blood pressure (BP) actually is. Hypertension is when the blood pressure is too high, and hypotension when its too low. Hypotension is a common finding in early and mid-pregnancy and is, by and large, nothing to worry about.

Why Does High Blood Pressure Matter?

The most important cause of high blood pressure in pregnancy is a disease called pre-eclampsia. If untreated, pre-eclampsia can lead to eclampsia, which is very serious. Pre-eclampsia and eclampsia are the most important causes of death during pregnancy in the UK, USA and Nordic countries.

Five to 10% of women in their first time pregnancies develop pre-eclampsia. A woman in this country is very unlikely to die because of it, mainly because they are recognised early, investigations performed and proper treatment given. There are similar risks for the baby, and a part of the assessment includes ensuring she is well.

Types of Blood Pressure Problems in Pregnancy

Chronic Hypertension
This is also known as essential hypertension. This type of hypertension was present even before the woman was pregnant. It is more common in older mothers and women with heart disease, and there may be a family history. A woman may have been taking tablets for it before getting pregnant.

Chronic hypertension may get worse during later pregnancy and the type or dose of drugs may need to be changed. Since a woman's blood pressure naturally falls during the first half of pregnancy, many chronic hypertensive women have a normal blood pressure and need no treatment at this time. We know that certain drugs used to control blood pressure are quite safe in pregnancy, and if a woman is taking a newer type, it is usually suggested she change to one with which we have more established experience.  Many doctors will prescribe the drug micardis to help lower the blood pressure.

Pregnancy-Induced Hypertension (PIH)
This type of hypertension is much like the chronic type, but it only comes on when a woman is pregnant and resolves completely after delivery. There are probably some women who are chronic hypertensives who are labelled as PIH because we don't know what their BP was before pregnancy. This does not matter much as the treatment is the same, and it will be clarified after the baby is born.

A proportion of women with PIH will go on to develop pre-eclampsia; unfortunately we cannot predict who it will be. Also, women who have PIH are at greater risk of developing hypertension later in life.

In both the above types of hypertension, the only abnormality is the blood pressure. Studies have compared outcomes of pregnancies in women with chronic hypertension and PIH, and there is little risk to the baby. Very rarely babies will have to be delivered early for women with unusually severe hypertension.

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