14 February 2011

Keeping mum

During pregnancy your heart has to pump 50% harder than normal – and that's just one of the changes to expect.


The body makes a series of fantastic adaptations during pregnancy, many of them almost as impressive as the new life growing in the womb.

The heart is most affected: we increase cardiac output by 50% – the amount of blood pumping through the system in one minute – as well as decreasing blood pressure. Things get even more complicated during labour and delivery, as blood moves from the uterus to the body, causing abrupt changes in blood pressure, heart rate and cardiac output.

The anaesthetic can also cause a drop in blood pressure to decrease. Then after delivery output increases and your heart rate slows. So, it’s no wonder that as many as one in 100 women are affected by heart-related problems in pregnancy.

What problems are common?
Many pregnant women develop heart murmurs, due to the increased blood flow. Normally this isn’t a problem, and your doctor can determine whether it needs further attention or not.

Another problem that may be picked up during pregnancy is an arrhythmia – fast or slow heartbeats that can be regular or irregular. Often there are no symptoms and no treatment is required, but sometimes they can cause palpitations, dizziness or light-headedness, even fainting. If you experience these symptoms your doctor will check you for arrhythmias. You may have an ECG or be asked to wear a heart monitor for a day.

High blood pressure, or hypertension, is a common complication in pregnancy. About 8% of all pregnant women develop hypertension, especially in the third trimester. Have your blood pressure tested at every check-up.

Very high blood pressure, along with rapid weight gain, swollen ankles and protein in the urine, is a symptom of ‘toxaemia of pregnancy’, more commonly known as pre-eclampsia.

The disorder affects your blood vessels, kidneys, liver and brain. Because pre-eclampsia can cause less blood to flow through the placenta and slows the growth of the foetus, it often leads to a pre-term delivery.

Pre-eclampsia is one of the leading causes of premature birth. This is a very serious medical condition and requires immediate medical attention.

What warning signs can you look out for?
Unfortunately the common symptoms of heart disease are similar to normal pregnancy niggles!

Symptoms may include:

  • difficulty breathing, especially at night
  • shortness of breath during normal activities
  • light-headedness or fainting
  • palpitations (irregular heartbeat)
  • heart murmur or click
  • enlarged heart (more than the normal enlargement with pregnancy)
  • cyanosis (blue-colouring due to low levels of oxygen in the blood).

Dr Philip Zinn, an obstetrician/gynaecologist operating out of Cape Town, emphasises: “Maternal deaths from heart disease in pregnancy are most frequently due to late diagnosis of an underlying heart condition. Signs and symptoms usually present a week or so before, but they can be missed as they mimic normal pregnancy complaints.”

If in any doubt, consult your doctor immediately.

What if I already have a heart condition?
“If you know you have a cardiac problem, get assessed before you plan a pregnancy,” stresses Dr Zinn.

“Your cardiologist and obstetrician should both be involved in managing any heart disease during the pregnancy.” Together you can discuss your heart condition, plan for your pregnancy and think about what may be involved in caring for your child later.

Having a child when you have an existing heart condition means you need very good prenatal care. You may need to have diagnostic tests, such as a foetal cardiac scan at 22 to 24 weeks.

Some medicines should not be used in pregnancy as they may harm your baby, so your doctor will prescribe heart drugs that won’t cause any damage. Most heart conditions can be managed through pregnancy, but two of particular concern are mitral stenosis and aortic stenosis.

The changes your body undergoes during pregnancy can cause problems for women with these conditions, which may require intensive care and medication. Women with severe aortic stenosis may even be advised against becoming pregnant.

Diabetes during pregnancy
As many as 7% of women become diabetic in pregnancy, or have their diabetes diagnosed in pregnancy. This condition is known as GDM, or Gestational Diabetes Mellitus.

Pregnant mothers, especially obese women or those with a family history of diabetes, should have a glucose test as soon as possible in pregnancy, and again between 24 and 28 weeks.

If your levels are raised you’ll have to change your diet, monitor sugar levels and may have to take insulin. If you’re diabetic, get professional advice before you fall pregnant.

Although there is a risk of congenital malformations, treatment to keep glucose levels stable during preconception and the first trimester has reduced this risk.

Healthy mom, healthy baby
Whether you have problems or cruise through your pregnancy, every woman should take precautions.

Eat a healthy diet, avoid alcohol and cigarettes, and check with your doctor or pharmacist before taking any medicine, including over-the-counter drugs.

Trust your instincts, and if anything seems wrong ask for medical advice. Remember that the fantastic machine that is our body has been coping with pregnancy for a very long time. If we treat it properly, we give our babies and ourselves the best possible chance for a healthy life.

(Karen Jeynes, Heart Magazine, September 2006)

Read more:
Diet and pregnancy blood pressure
Is it okay to become pregnant if I have hypertension?


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