Gestational Diabetes - what is it and how to reduce your risk

By Mater Mothers' Hospital

Gestational Diabetes Mellitus (GDM) is a specific type of diabetes that only occurs during pregnancy. It is usually a temporary condition that goes away after the birth of the baby, however can have significant effects for both mother and baby if not well controlled throughout the pregnancy.

Approximately 1 in 20 pregnant women may develop gestational diabetes, usually between 24 and 28 weeks of pregnancy.

“GDM occurs as a result of changes in hormone levels as pregnancy progresses, which can interfere with how some women’s insulin works,” Mater Mothers’ Hospitals Parent Education Unit Manager Michelle O’Connor explains.

“Insulin helps the body to process glucose (sugar) from the blood into the muscles for energy and into the liver for storage and energy.”

You have an increased risk of developing gestational diabetes if you:

  • Are aged over 30
  • Have a family history of Type 2 diabetes
  • Are overweight
  • Are from certain ethnic backgrounds— Indigenous Australian, Torres Strait Islander, Indian, Vietnamese, Chinese, Middle Eastern, Polynesian  or Melanesian
  • Have had gestational diabetes in a previous pregnancy
  • Have previously had difficulty carrying a pregnancy to term
  • Have previously birthed a baby weighing more than 4 kg.

How is Gestational Diabetes diagnosed?

The Australasian Diabetes in Pregnancy Society recommends testing for gestational diabetes in all pregnant women. An Oral Glucose Tolerance Test will be performed between 26 and 28 weeks of pregnancy.

“The oral glucose tolerance test involves taking a blood test before and two hours after drinking a sugary drink,” Michelle said.

“This test may be performed earlier in your pregnancy if there is a clinical reason to do so”.

How is Gestational Diabetes treated?

“The aim of treatment is to maintain your blood glucose levels, or the levels of sugar in your blood, within a normal range for the rest of your pregnancy,” Michelle said.

For most women this can be achieved by:

  • Following a healthy diet — a dietitian will provide information to assist you
  • Having a healthy weight gain during pregnancy
  • Exercising regularly

Approximately 1 in 10 women with gestational diabetes will require insulin injections during pregnancy to maintain normal blood glucose levels. As gestational diabetes usually occurs later in pregnancy, your baby’s physical development is not affected.  However, because glucose crosses the placenta your baby is exposed to your higher blood glucose levels. This stimulates your baby’s pancreas to produce more insulin and it is the extra insulin that causes your baby to grow bigger and put on weight.

“In the first few days following birth, the baby will be closely monitored and it can take several days for the baby to adjust,” Michelle said.

“The baby’s blood glucose levels may be tested regularly until their levels remain within normal range.”

You can help your baby by:

  • Maintaining healthy blood glucose levels during pregnancy
  • Breastfeeding within one hour of birth and continuing to feed, at least every three hours, until your milk comes in (this usually occurs on the third day after birth)

Following a healthy diet, having a healthy weight gain during pregnancy and exercising regularly will help to  control your blood glucose levels during pregnancy.

“Gestational diabetes is primarily managed by following a healthy well balanced eating plan, taking into consideration carbohydrate intake and physical activity,” Mater Mothers’ Hospitals Senior Maternity Dietitian Elin Donaldson explains.

“If women cannot manage their blood glucose levels with diet and activity alone, medication such as insulin (injections) or metformin (tablets) is sometimes needed.”

Although some foods such as carbohydrates put glucose into our blood stream, cutting these foods out completely means cutting out all the nutritious goodness needed for a healthy pregnancy and a growing and developing baby.

What should I eat to reduce my risk?

  • Base your meals on wholegrains, lean proteins, fruits and vegetables
  • Choose a diet low in saturated fat – choose low fat dairy foods, lean meats and skinless chicken, and limit biscuits, chips, cakes, pastries, processed fried and takeaway foods
  • Include small amounts of the healthy poly or monounsaturated fats and oils such as canola, olive or sunflower oils and margarines, avocado and unsalted nuts
  • Choose lower glycaemic index (GI) carbohydrate foods such fresh fruit, grainy bread, low fat dairy foods, pasta, basmati rice and low GI cereals
  • Eat regular meals and watch your portion size
  • Avoid high sugar drinks (e.g. cordials, soft drinks) and choose water as your everyday drink.

Ongoing, regular contact with diabetes educators, dietitians, specialists and attendance at antenatal clinics during pregnancy is important for good blood glucose levels and best outcomes for mother and baby.

What happens after the birth?

In most cases, Gestational Diabetes goes away after birth, however, there is a 40 per cent chance of developing Gestational Diabetes in your next pregnancy and an increased chance of developing Type 2 diabetes later in life. Breastfeeding is protective for the mother and you are less likely to develop this condition if you are able to breastfeed your baby.

You will be asked to repeat your glucose tolerance test six to eight weeks after your baby’s birth.

Note: The views and advice expressed on this blog post are those of the author and are not representative of the Pregnancy Babies & Children's Expo.

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