What you need to know about pregnancy if you have diabetes

If you have diabetes, it can affect all stages of pregnancy from conception to delivery. However, if you maintain healthy blood glucose levels before and during your pregnancy, you have a good chance of delivering a healthy baby.

This page focuses on pregnancy when you already had diabetes before getting pregnant. There is also a condition called gestational diabetes, which is when you develop diabetes during a pregnancy. Read about diabetes that develops during pregnancy.

Key points about pre-existing diabetes and pregnancy

  1. Pre-existing diabetes means you have diabetes before you get pregnant. This is different from gestational diabetes which is a kind of diabetes that some women get during pregnancy.
  2. Women who have diabetes before pregnancy are at increased risk of pregnancy complications.
  3. The higher the blood glucose level, the higher the risk of complications.
  4. Having good control of the blood glucose levels before pregnancy is the best way to decrease the risk of these complications.
  5. Most women with diabetes before pregnancy will have a safe pregnancy and a healthy baby but will need extra care.

How can having diabetes affect pregnancy?

Diabetes can cause problems in pregnancy for both you and your baby.

Risks to your health

If you have type 1 or type 2 diabetes, you may be at higher risk of:

  • having a very large baby – which increases the risk of a difficult birth
  • having your labour induced or needing a caesarean section
  • having a miscarriage
  • developing high blood pressure and pre-eclampsia
  • gum disease, bladder and other infections.

Pregnancy also makes your blood glucose increase and this makes your diabetes more difficult to control. If you already have eye, kidney, heart or nerve problems, pregnancy can make these worse.

Risks to your baby's health

The most common problems for babies born to mothers with pre-existing diabetes are:

  • being born early
  • having breathing problems or low blood sugar levels after birth
  • being admitted to a special care baby unit.

Your baby is also at a higher risk of some uncommon but serious problems such as: 

  • being born with birth defects, particularly affecting the heart, kidney or spine
  • being stillborn
  • being born very early
  • having a very difficult birth (called shoulder dystocia).

Managing your diabetes well before and during your pregnancy definitely helps to reduce these risks.

Planning your pregnancy

The best way to reduce the risks to you and your baby is to ensure your diabetes is well controlled before you become pregnant. Let your GP or diabetes specialist know 3–6 months before you start trying for a baby. They can refer you to a diabetes clinic for pre-pregnancy counselling and support. 

Your blood glucose levels need to be closely monitored. You should be offered a blood test, called an HbA1c test, every month. This measures the level of glucose in your blood. Continue using contraception and delay getting pregnant until your blood glucose is well controlled (HbA1c is under 48mmol/mol or your personal target is met). However, not everybody can plan their pregnancy. If you have diabetes and think you might be pregnant, see your doctor as soon as you can. 

Your healthcare team will review your medicines. If you are taking sulphonylurea to control your diabetes, this is likely to be stopped and replaced with insulin. Medicines such as statins or ACE inhibitors will also be stopped as they can cause harm to the development of your baby. 

Folic acid

Women with diabetes should take a higher dose of 5 milligrams (mg) of folic acid each day while trying to get pregnant and until you are 12 weeks pregnant. Your doctor will have to prescribe this, as 5mg tablets are not available over the counter.

Taking folic acid helps to prevent your baby from developing birth defects, such as spina bifida. Your doctor will also prescribe iodine 150 micrograms daily for you to take. 

Other things you can do

  • Eat a healthy balanced diet as guided by your dietitian.
  • Stay active – aim for at least 30 minutes of exercise, such as walking or swimming, 5 or more days each week.
  • Aim for a healthy body weight.
  • Avoid alcohol, smoking and recreational drugs.
  • Make sure your vaccinations are up to date.

During pregnancy

A specialist diabetes and pregnancy team will care for you during your pregnancy. The team is likely to include a diabetes specialist, an obstetrician (a doctor who specialises in pregnancy and childbirth), a midwife or specialist diabetes midwife, a dietitian and a diabetes nurse educator.

  • You will need to test your blood glucose levels more frequently during your pregnancy, especially since nausea and vomiting (morning sickness) can affect them. Most people test between 4–8 times a day during pregnancy.
  • You will also be asked to get frequent laboratory blood glucose and HbA1c levels during pregnancy. These are to back up the results you are getting on your own blood glucose meter. 
  • Your doctors may recommend changing your diabetes treatment during pregnancy. Depending on your blood glucose levels, you may be started on insulin. You will receive support and education about insulin from the diabetes midwife or diabetes nurse educator. 
  • It's very important to attend any appointments made for you so that your care team can monitor your condition and react to any changes that could affect your or your baby's health.
  • You are likely to have frequent scans during your pregnancy. Scans are a good way of checking on the baby’s growth and development.
  • Keeping your blood glucose levels low may mean you have more low-blood-sugar (hypoglycaemic) attacks ("hypos"). These are harmless for your baby, but you and your partner need to know how to cope with them. Talk to your doctor or diabetes specialist.

Insulin pumps and continuous glucose monitoring

Many women with diabetes before pregnancy will be treated with insulin during pregnancy. There have been technological advances in the treatment of diabetes and these advances are now being used for some women when they are pregnant.

Most women give themselves injections of insulin after each meal and in the evening. Insulin pumps can be programmed to give insulin more regularly throughout the day which is closer to the way that insulin is normally produced.

Continuous glucose monitors are machines which are stuck to your skin and which monitor the glucose levels every minute. They have been shown to improve blood glucose control compared to finger-prick testing.

During labour and delivery 

You should plan the birth together with your doctor and midwife. Your doctors may recommend having your labour started early (induced) because there may be an increased risk of complications for you or your baby if your pregnancy carries on for too long.

If your baby is larger than expected, your doctors might discuss your options for the delivery and may suggest an elective caesarean section.

Your blood glucose levels will be checked at least every hour during labour. You may be given a drip in your arm with glucose and insulin. The amount of glucose and insulin can be changed according to your blood glucose levels.

When your baby is born

Feed your baby as soon as possible after the birth – within 30 minutes – to help keep their blood glucose at a safe level. Your baby will be monitored closely and may have blood tests regularly. This is to test for low sugar levels, not diabetes. If your baby’s blood glucose can’t be kept at a safe level, or they are having problems feeding, they may need to go to the special care nursery for a day or two.

You should be able to start eating fairly soon after your baby is born. If you were given a glucose and insulin drip this will be stopped. Your blood glucose levels will be checked often.

Insulin is the safest diabetes medicine to take if you are breastfeeding. However, once you stop breastfeeding you can consider diabetes tablets again.

Once you go home, your diabetes team will stay in contact with you until your blood glucose levels are healthy and you are settled on the medication you are taking for your diabetes.

Learn more

Pregnancy Diabetes New Zealand
Pre-Existing Diabetes and Pregnancy CDC, Department of Health, US


  1. Monitoring diabetes before, during and after pregnancy BPAC, NZ, 2015
  2. Diabetes in pregnancy: management from preconception to the postnatal period NICE, UK, 2015
  3. Diabetes in pregnancy ADHB, accessed 14 October 2019
  4. Continuous glucose monitoring in pregnant women with type 1 diabetes (CONCEPTT): a multicentre randomised controlled trial Lancet, UK, 2017

Reviewed by

Dr Jeremy Tuohy is an Obstetrician and Gynaecologist with a special interest in Maternal and Fetal Medicine. Jeremy has been a lecturer at the University of Otago, Clinical leader of Ultrasound and Maternal and Fetal Medicine at Capital and Coast DHB, and has practiced as a private obstetrician. He is currently completing his PhD in Obstetric Medicine at the Liggins Institute, University of Auckland.
Credits: Health Navigator Editorial Team . Reviewed By: Dr Jeremy Tuohy, Obstetrician & Researcher, University of Auckland Last reviewed: 23 Apr 2021