What is Gestational Diabetes?

Gestational diabetes is a form of diabetes that occurs during pregnancy and usually goes away after the baby is born. It is diagnosed when higher than normal blood glucose levels first appear during pregnancy. Between 12% to 14% of pregnant women will develop gestational diabetes and this usually occurs around the 24th to 28th week of pregnancy.

All women should be checked for gestational diabetes by taking a special blood test. Women who have one or more of the risk factors listed below are advised to have a diabetes test when pregnancy is confirmed then again at 24 weeks if diabetes was not detected in early pregnancy.

While maternal blood glucose levels usually return to normal after birth, there is an increased risk for the mother developing type 2 diabetes in the future. The baby may also be at risk of developing type 2 diabetes later in life.

Who is at Risk?

You are at risk of developing gestational diabetes if you:

  • are aged 40 years or over
  • have a family history of type 2 diabetes or a first-degree relative (mother or sister) who has had gestational diabetes
  • are above the healthy weight range » have had elevated blood glucose levels in the past
  • come from Aboriginal or Torres Strait Islander backgrounds
  • are from a Melanesian, Polynesian, Chinese, Southeast Asian, Middle Eastern or Indian background
  • have had gestational diabetes in a previous pregnancy
  • have polycystic ovary syndrome
  • have previously had a large baby (weighing more than 4.5kg)
  • are taking some types of antipsychotic or steroid medications
  • have gained weight too rapidly in the first half of pregnancy

What causes gestational diabetes?

In pregnancy, the placenta produces hormones that help the baby to grow and develop. These hormones also block the action of the mother’s insulin. This is called insulin resistance. Because of this insulin resistance, the need for insulin in pregnancy is 2 or 3 times higher than normal. If the body is unable to produce this much insulin, gestational diabetes develops.

Gestational Diabetes information sheet