Gestational diabetes: What it means for you and your baby

Is diabetes during pregnancy caused by eating sweets? Kaye Foster-Powell explores the causes behind gestational diabetes and how it can be managed.

Gestational diabetes (GD) is the medical term given for diabetes first diagnosed during pregnancy. For many women it can be an upsetting diagnosis, but despite what many people think, it isn't caused by eating sweets.

Who is at risk?

GD occurs in about five per cent of pregnancies but the incidence is increasing. In Pacific Island, Indian and Asian women the incidence may be as high as 10 per cent.

A woman is more likely to develop GD if she has certain risk factors, but it can develop in a woman who has no risk factors.

Risk factors for GD

• family history of diabetes
• being overweight
• over 25 years of age
• multiple pregnancy, ie. twins or more
• history of gestational diabetes or complicated pregnancy

Why does it happen?

During pregnancy, hormonal changes occur in a woman's body to ensure a steady supply of glucose, as fuel, to the growing baby. One of the changes in the mother is the development of 'insulin resistance' which means her body doesn't take up glucose as readily as usual. This is thought to help channel glucose to the baby in preference to the mother.

Women with GD have a greater severity of insulin resistance than that seen in normal pregnancies and are unable to produce enough insulin to control their own blood glucose levels. Consequently, their blood glucose levels rise above the normal range for pregnancy.

Why is it a problem?

Gestational diabetes has health implications for a mother and her baby. One of the most widely recognised health implications is the risk of the baby growing too fat during pregnancy which can lead to complications in delivery. Untreated GD puts the baby at risk of growing disproportionately fat while in utero and suffering breathing difficulty, jaundice and low blood glucose (hypoglycaemia) at birth. It also puts the mother at increased risk of high blood pressure and pre-eclampsia.

The good news is, control of the mother's blood glucose levels during pregnancy can prevent these complications.

After pregnancy, women who have had GD have a very high risk of developing type 2 diabetes later in life. There is also increasing evidence that GD influences the future health prospects of the child, with children of mothers who had GD found to be at higher risk of obesity and diabetes in later life.

How do I know if I have it?

General symptoms such as thirst, lethargy, increased hunger, urinary tract infections (UTIs) and vaginal thrush – which are often put down to simply being pregnant – can also be signs of GD.

It is recommended all pregnant women should consider being tested for GD at 26-28 weeks gestation, especially those with risks factors. Testing involves measuring the woman's blood glucose response to a glucose drink (a glucose challenge test). If this test reads high, the woman will then do a fasting test over two hours.

How is it managed?

Gestational diabetes is managed with healthy eating, exercise and regular blood glucose monitoring. Some women will need to have more tailored carbohydrate portions for their meals, and some may need to have insulin injections as well. The insulin won't harm the baby – it is a copy of what the woman's body normally makes.

Tips to help control your blood glucose levels

• Eat regularly – little and often is far better than large and irregular meals.
• Choose low-GI carbohydrate – whole grain breads, cereals such as low-GI mueslis, rolled oats and All-Bran, legumes, fruit and low-fat dairy products.
• Moderate the amount of carbohydrate you eat – avoid eating large meals of pasta, rice, bread or potato. Include these carbohydrate foods at different meals across the day in combination with vegetables, salads and lean protein foods.
• Minimise foods high in saturated fat – this includes crisps, pastries, takeaways, butter and cream, biscuits and cakes.
• Limit sugary foods and drinks – including soft drinks, cordials, confectionery and desserts.

Common questions

Will I be able to breastfeed?
Having GD does not affect your ability to breastfeed. Breast milk is the optimal source of nutrition for a baby and recommended as the sole food until the baby is around six months old. Breastfeeding may lower a child's future risk of diabetes and a recent study suggested that it may even reduce a woman's risk of developing type 2 diabetes.

Will I get GD in my next pregnancy?
The rate of recurrence of GD varies but most women who have had GD in one pregnancy will develop it again in future pregnancies. In fact, blood glucose levels should be checked earlier in subsequent pregnancies because of the risk of undiagnosed diabetes or pre-diabetes between pregnancies.

How can I reduce my risk of diabetes in the future?
If you have had GD, it is important to try to achieve and maintain a healthy body weight and a good level of physical fitness after pregnancy. Eat a healthy diet which is low in saturated fat, rich in fruit, vegetables, legumes, fish and whole grains, and include regular physical activity.

The good news

• If blood glucose levels are controlled, a woman can safely expect a full-term pregnancy and a normal delivery.
• The baby will have no greater risk of being born with diabetes.
• Chances are your diabetes will go away as soon as the baby is born. There is, however, an increased risk of diabetes in the future, so it is important to have your blood glucose checked six to 12 weeks after delivery and annually after that.

For more information, visit:
Diabetes New Zealand
Australian Diabetes in Pregnancy Association