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Diabetes in pregnancy (gestational diabetes)

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You may already have diabetes or develop gestational diabetes during pregnancy. This means you need to be referred to the specialist diabetes team at the hospital. You can continue to receive care from your midwife, LMC or GP in the community as well.

Gestational diabetes

Hormones made in the placenta during late pregnancy make it harder to control blood glucose (sugar) levels.

Some women cannot make enough insulin to keep up with these changes, and their glucose levels rise causing gestational diabetes.

When the mother's glucose levels rise, so does the baby's, which can make it produce too much insulin. This can make the baby grow too much and has other harmful effects.

You're more at risk of getting gestational diabetes if you:

are overweight
have a family history of diabetes
have polycystic ovary syndrome
have had gestational diabetes before
have prediabetes (impaired glucose tolerance)
are from certain ethnic groups, such as Māori, Pasifika, Chinese, Indian and South-East Asian.

Gestation diabetes is usually temporary and goes away after your baby is born. But you have a higher risk of getting Type 2 diabetes in the future so you should have a diabetes test every year.

Diabetes New Zealand has more information on gestational diabetes.

Testing for gestational diabetes

All pregnant women are offered an antenatal blood test early in their pregnancy. This includes the HbA1c test, which screens for diabetes.

Between 27 and 28 weeks of pregnancy, you'll be offered a screening blood test called the polycose test. For this test, they will give you a drink containing glucose. They will then take a sample of your blood one hour later. If the test is high, you'll need to have a second test, called the glucose tolerance test.

If your lead maternity carer thinks you might be getting diabetes after 28 weeks, they may screen you again later in your pregnancy.

Treating gestational diabetes

You can usually manage gestational diabetes with healthy eating and regular physical activity.

Some people might need metformin tablets or insulin injections.

For more information about managing gestational diabetes, see Online education for diabetes in pregnancy. The page includes videos with advice about eating well to manage gestational diabetes and about testing blood glucose levels.

Type 1 diabetes

If you have type 1 diabetes, you'll be taking insulin to control your blood glucose levels. It's important to have good control of your glucose levels before becoming pregnant. This is to avoid unnecessary complications. Insulin is safe in pregnancy, and you should keep using it.

If possible, see your GP or diabetes specialist in the months before you plan to become pregnant. You should also take a higher dose of folic acid than women without diabetes (5 mg daily). You'll need a prescription from your doctor for this.

Type 2 diabetes

If you have type 2 diabetes, you may be taking medication to control your blood glucose levels. It's important to have good control of your glucose levels before becoming pregnant. This is to avoid unnecessary complications.

If possible, see your GP or diabetes specialist in the months before you plan to become pregnant. This is so they can make any necessary adjustments to your medication.

If you become pregnant unexpectedly, don't stop your medication. Make an appointment to see your GP as soon as possible.

Try to maintain a healthy weight both before and during your pregnancy. You should also take a higher dose of folic acid than women without diabetes (5 mg daily). You'll need a prescription from your doctor for this.

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