High blood pressure can be dangerous for both the mother and her unborn baby, especially in early stages of pregnancy. Experts warn that women with hypertension are more likely to have

babies with birth defects as well as stroke and heart disease in future, without adequate treatment, reports Sade Oguntola.

HAVE you ever wondered why your blood pressure is always checked at every antenatal appointment? Measuring the blood pressure is an important part of health care. It is an important part of looking after a woman in pregnancy and her unborn child.

High blood pressure, or hypertension, associated with pregnancy can be a serious problem. While most pregnant women who have, or develop, high blood pressure during pregnancy go on to complete a natural birth with no serious problems, the condition can still be dangerous.

About six per cent of women with no history of high blood pressure will spontaneously develop high blood pressure during pregnancy. This condition is referred to as gestational hypertension or Pregnancy Induced Hypertension (PIH) and it usually disappears after delivery.

Blood pressure is the amount of force exerted by the blood against the walls of the arteries. A person’s blood pressure is considered high when the readings are greater than 140 mm Hg systolic (the top number in the blood pressure reading) or 90 mm Hg diastolic (the bottom number).

Dr Adebola Roberts, a consultant obstetrician and gyneacologist, University College Hospital (UCH), Ibadan, Oyo State, stated that hypertension whether it predates a pregnancy or occurs in pregnancy when left attended to can be dangerous for the health of both the mother and her unborn baby.

Although many pregnant women with high blood pressure have healthy babies without serious problems, women with pre-existing, or chronic, high blood pressure are more likely to have certain complications during pregnancy than those with normal blood pressure.

In addition, women with high blood pressure (hypertension) in early stages of pregnancy, a study suggested, are more likely to have babies with birth defects, irrespective of commonly prescribed medicines for their condition.

The scientists indicated in the British Medical Journal (BMJ) that it is the underlying hypertension, rather than the use of antihypertensive drugs in early pregnancy that increases the risk of birth defects.

What is more, their risk of heart attack, stroke and other problems associated with high blood pressure does not go away during pregnancy, either, if the high blood pressure persists.

The effects of high blood pressure range from mild to severe. High blood pressure can harm the mother’s kidneys and other organs, and it can cause low birth weight and early delivery. In the most serious cases, the mother develops preeclampsia - or “toxemia of pregnancy”—which can threaten the lives of both the mother and the unborn child.

Preeclampsia is a condition that typically starts after the 20th week of pregnancy and is related to increased blood pressure and protein in the mother’s urine (as a result of kidney problems).

Preeclampsia affects the placenta, and it can affect the mother’s kidney, liver, and brain. It is also a leading cause of complications in an unborn baby, which include low birth weight, premature birth, and stillbirth.

According to Dr Roberts, pregnancy induced hypertension was a far more serious problem than the established or pre-existing hypertension if it was left untreated.

He explained: “This is so because certain immunological changes which occur as a result of pregnancy prevent the blood vessels from behaving the way they should normally do, thus retaining a high blood pressure that actually harms the baby inside the womb.”

As a result of the high blood pressure, there is reduction in the baby’s supply of oxygen and nutrients, potentially slowing the baby’s growth and increasing the risk of a low birth weight and still birth.

It is still not known why certain women develop high blood pressure during pregnancy. However, certain pre-existing conditions that increase the risk of developing high blood pressure include diseases such as diabetes, kidney disease and rheumatoid arthritis.

Women with their first babies, carrying twins or triplets or whom in their previous pregnancy developed pre-eclampsia or were obese stand a higher risk of experiencing pregnancy induced hypertension.”

But high blood pressure should not be a barrier to being a mother or having a healthy baby. Even when there is a preeclampsia that is superimposed on a pre-existing blood pressure, Dr Roberts said, there are medical interventions that can assist such women.

“Women who developed high blood pressure or preeclampsia during a previous pregnancy are recommended to take a low dose of aspirin daily from about the 16th week of pregnancy until about the 35th week of pregnancy. By this period, the chances of survival of the baby are improved and almost guaranteed.

“However, for those who are having the challenges in the index pregnancy (pregnancy that is affected by the disease), drugs are prescribed to control the raised blood pressure as well as other side effects of high blood pressure both on the unborn baby such as intrauterine growth retardation as well as the mother.

“The timing of the delivery is then determined by all that happens both to the mother and her baby, either until the baby can live outside of the womb or the health of the mother permits that the pregnancy be retained.

“Even when the baby has not matured enough for it to live outside the womb but the life of the mother is threatened, then we must terminate the pregnancy.” Dr Roberts explained.

In addition, women thinking about having a baby and who have high blood pressure need to talk first to their doctor. Taking steps to control the blood pressure before and during pregnancy and getting regular prenatal care will go a long way towards ensuring the mother’s well-being and a healthy baby.

Lifestyle changes such as limiting salt intake, participating in regular physical activity, and losing weight if overweight can be helpful. In addition, there might be the need for adjustment in hypertension medicines being used.

Experts currently recommend avoiding angiotensin-converting enzyme (ACE) inhibitors and Angiotensin II (AII) receptor antagonists during pregnancy.

Nonetheless, experts warn that women with high blood pressure during pregnancy have a higher risk of experiencing high blood pressure, kidney problems, and stroke in the future.

This was based on a study of female residents of Rochester, Minnesota and the surrounding townships in Olmsted County who delivered between 1976 and 1982.

They divided the women into two groups, those with high blood pressure during pregnancy and those without, and followed them after they reached 40 years of age to monitor their heart and kidney health. A total of 6,051 mothers delivered between 1976 and1982, and 607 women had high blood pressure at the time while 5,444 did not.

After they reached age 40, they found higher incidence of high blood pressure, kidney disease, and strokes in women who had high blood pressure during pregnancy than women who did not have high blood pressure during pregnancy.

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