How gestational diabetes can affect your pregnancy

Diabetes in pregnancy (gestational diabetes)

If a screening test shows that you have gestational diabetes, it is important to understand what this means for your pregnancy and birth.

Most people with gestational diabetes have a healthy pregnancy and give birth to a healthy baby. Sometimes, however, gestational diabetes can cause complications that affect you and your baby during pregnancy and after birth.

When you are diagnosed with gestational diabetes, we monitor your pregnancy more closely. Our specialist diabetes team supports you to manage the condition. 

To avoid complications and keep you and your baby healthy, you need to control your blood sugar levels. We give you advice about:

  • checking your blood sugar levels
  • eating a healthy, balanced diet
  • keeping active and managing your weight

Sometimes, we give you diabetes medicines to help treat the condition.

Gestational diabetes usually goes away after your baby is born. You are more likely to get gestational diabetes if you become pregnant again, or type 2 diabetes (a lifelong type of diabetes). A healthy lifestyle reduces the chance of future complications.

Possible complications of gestational diabetes

If you have gestational diabetes, your baby may grow to a larger than average size. This can cause complications for you and your baby at birth.

You may also be more likely to get a condition called pre-eclampsia. This is when you have high blood pressure, swelling and protein in the urine.

Go to our maternity assessment unit or call NHS 111 immediately if you:

  • have a severe headache
  • have eyesight problems, such as blurring or flashing
  • have pain just below the ribs
  • are being sick (vomiting)
  • have sudden swelling of the face, hands or feet

These could be signs of pre-eclampsia. Also get urgent medical advice if you are worried that your baby is not moving as much as usual. Our maternity assessment unit is open 24 hours a day, 7 days a week.

Depending on your personal circumstances, we recommend when it is best to give birth if you have gestational diabetes. 

  • If your baby is growing as expected and your blood sugar levels are well controlled, we recommend giving birth before 41 weeks.
  • We may recommend giving birth earlier to reduce risks to you or your baby during childbirth. This depends on your ultrasound scans and blood sugar management. We do not usually recommend giving birth before 38 weeks of pregnancy.

If you do not give birth naturally by the recommended time, we might offer you:

Sometimes, babies can have low blood sugar when they are born as they adapt to their new environment. For this reason, we check your baby’s blood sugar level before they feed.

After having gestational diabetes, you are more likely to get type 2 diabetes. Your baby may also have a higher chance of being overweight or getting type 2 diabetes later in life. Having a healthy lifestyle reduces the chance of long-term complications.

Monitoring your pregnancy

If you are diagnosed with gestational diabetes, you will continue to see your midwife at your home, GP surgery or clinic.

We also ask to review you in the diabetes clinic. Your appointments can be face to face at the hospital or by phone. Diabetes doctors, nurses and obstetricians (doctors specialising in pregnancy) can then help to monitor your pregnancy.

You have extra antenatal appointments to:

  • check how well your blood sugar levels are controlled
  • monitor your pregnancy more closely

We also offer you extra scans to check how your baby is growing.

Controlling your blood sugar levels

Controlling your blood sugar levels while you are pregnant and in labour helps to keep you and your baby healthy.

Checking your blood sugar (glucose) levels

We teach you how to use a blood glucose monitoring meter and give you a book to record the results.

We need to get a complete picture of your blood sugar levels. For this reason, we ask you to test your blood sugar:

  • before you eat in the morning (your fasting level)
  • 1 hour after each meal

For most people, this means doing 4 blood tests a day.

Your target blood sugar levels are:

  • less than 5.3mmol/L after fasting
  • less than 7.8mmol/L 1 hour after meals

For more information about checking your blood sugar levels, please visit the Diabetes UK website.

Lifestyle changes

Having a healthy lifestyle can help you to control your blood sugar levels and manage gestational diabetes. It is important to:

  • eat a healthy, balanced diet
  • keep to a healthy weight
  • stay active and do regular exercise

However, it is not a good idea to start dieting when you are pregnant. You can see one of our dietitians for advice about planning healthy meals if you have gestational diabetes.

One of our midwifes has helped to write a book called "Tasty recipes when you have gestational diabetes". This book includes 40 culturally sensitive recipes and various healthy eating tips. It is intended to help you manage gestational diabetes in pregnancy and after you have had your baby.

The diabetes team can give you advice about safe ways to exercise in pregnancy.

Diabetes medicines

It may be possible to control your blood sugar levels by changing your diet and lifestyle. If your blood sugar is still not stable, you may need to take tablets, insulin injections or both. These medicines are not harmful and are often used in pregnancy.

Giving birth

The obstetricians (doctors specialising in pregnancy) talk to you about your options for giving birth. They make a birth plan with you when you are about 36 weeks pregnant.

Your options include:

The date that we recommend these options depends on the circumstances of your pregnancy. We talk to you about the benefits and risks of each option. Your birth plan depends on your individual situation and preferences.

You may be able to wait for labour to start naturally if:

  • your blood sugar levels are well controlled
  • there are no concerns about your health or your baby’s health

However, we usually offer you an induction of labour or a caesarean section if you do not give birth by 41 weeks. This is because if your pregnancy goes on for too long, it may increase the risk of problems for you and your baby.

We might recommend giving birth earlier than 41 weeks if you have any pregnancy complications, such as:

We recommend that you have your baby in hospital. This allows us to monitor your baby’s heartbeat more closely and check your blood sugar levels when you give birth.

We might talk to you about if you want to give birth in our home from home birth centre at the hospital. Midwives care for you at this centre, which has 8 single rooms and 2 birthing pool rooms. The home from home birth centre might be a suitable place to give birth if:

  • you have an uncomplicated pregnancy
  • your baby is a healthy size
  • you do not need medicine to treat your baby

When your baby is born, we check their blood sugar levels in hospital while they get used to their new environment.

After birth

You are likely to have questions about breastfeeding your baby and checking your blood sugar levels after you give birth.

Breastfeeding your baby

It is fine to breastfeed your baby if you have gestational diabetes. Breastfeeding has many benefits for you and your baby.

Your midwife talks to you about expressing breast milk with your hand before your baby is born (antenatal hand expressing). This can be useful if your baby does not want to feed soon after birth or if their blood sugar levels are a little low.

Checking your blood sugar levels after birth

Usually, you can stop checking your blood sugar levels when your baby is born. However, the diabetes doctors and nurses need to confirm this when you see them at 36 weeks.

Long-term effects of gestational diabetes

It is important to be aware of some possible long-term effects of gestational diabetes and how you can avoid health problems.

Risk of type 2 diabetes

Gestational diabetes usually goes away when your baby is born. There is, however, a chance that you may have developed type 2 diabetes. This is a lifelong type of diabetes.

Your GP organises a blood test for you 3 months after your baby has been born to check your blood sugar level. If this is normal, you will have another test for diabetes once a year.

You can reduce your chance of getting type 2 diabetes later in life by:

  • eating a healthy, balanced diet
  • exercising regularly
  • keeping to a healthy weight

Planning future pregnancies

More than 1 in 3 people with gestational diabetes get this condition again if they have another baby.

If you do become pregnant again, it is important to see a midwife as soon as possible. You can then be tested for gestational diabetes early in your pregnancy and reduce complications.

Resource number: 4381/VER3
Last reviewed: May 2023
Next review due: May 2026

A list of sources is available on request.

Trusted Information Creator. Patient Information Forum

Contact us

If you have any questions or concerns about gestational diabetes, please speak to your midwife or a member of the diabetes team.


Out of hours, please leave a message and a member of staff will call you back in working hours. Otherwise, please contact your GP, go to or call 111.


Guy’s and St Thomas’ diabetes team:

[email protected]

We aim to respond to your email within 1 working day.

Pharmacy medicines helpline

If you have any questions or concerns about your medicines, please speak to the staff caring for you.

You can also contact our pharmacy medicines helpline.

Phone: 020 7188 8748, Monday to Friday, 9am to 5pm

Email: [email protected]

We aim to respond to emails within 2 working days.

Do you have any comments or concerns about your care?

Contact our Patient Advice and Liaison Service (PALS)

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