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Gestational diabetes (diabetes in pregnancy)

Gestational diabetes is a type of diabetes that you may develop when you’re pregnant and your blood glucose (sugar) level is too high. It’s also known as GDM, which stands for gestational diabetes mellitus. This condition can lead to problems for both you and your baby if you don’t control it. There are lots of treatments, as well as changes you can make to your lifestyle, that can help to reduce its impact on your pregnancy.

Open our infographic about the stages of pregnancy.

Your body produces a hormone called insulin to control the glucose level in your blood. When you’re pregnant, your hormones, such as oestrogen and progesterone, cause your cells to become less sensitive to insulin.

Your body needs to produce more insulin than usual to help control the high level of glucose in your blood. If you develop gestational diabetes, your body either doesn’t release enough insulin, or your cells don’t respond to it. The result is that your blood glucose level remains high. This can have a number of effects on you and your baby.

Around four in 100 pregnant women get gestational diabetes.

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How your baby develops, stages of pregnancy by Bupa UK


  • Symptoms Symptoms of gestational diabetes

    Gestational diabetes usually begins after the 12th week of being pregnant. You probably won’t notice any symptoms because it’s usually diagnosed in a screening test before symptoms develop. If gestational diabetes isn’t picked up in tests, you may develop symptoms. For example, you may:

    • feel thirsty more often than usual 
    • pass urine more often 
    • feel tired

    Some of these symptoms are quite common if you’re pregnant and aren’t always caused by gestational diabetes. But if you have them, tell your GP or midwife.

  • Diagnosis Diagnosis of gestational diabetes

    At your first antenatal appointment, your midwife will ask you some questions to assess your risk of gestational diabetes. Based on your answers, you may be offered a test later on in your pregnancy to find out if you’ve developed the condition.

    In this test, you will need to drink a sugary drink and then have blood samples taken. These will measure how well your body processes glucose. Your midwife will usually offer you the test when you’re between 24 and 28 weeks pregnant. But you might need to have the test earlier if you’ve had gestational diabetes before.

  • Treatment Treatment of gestational diabetes

    If you’re diagnosed with gestational diabetes, your midwife or GP will refer you to a joint diabetes and antenatal clinic. The doctors, nurses, midwives and dieticians in the team will be experienced in looking after pregnant women with diabetes. You will have more antenatal appointments than women who don't have gestational diabetes.

    Your treatment will aim to keep your blood glucose low enough to help prevent complications. You’ll need to test your blood regularly to check this. Your nurse will give you advice on how to test your blood glucose level, how often, and the level that you're aiming for.


    Your doctor or a dietitian will give you advice on ways to manage gestational diabetes by making changes to your lifestyle. This may involve making changes to your diet and how much exercise you do. This may be all you need to do to keep your blood glucose level low enough to help reduce the risk of complications.

    Eat a healthy balanced diet to help to keep your blood glucose level stable and within the ideal range. Include carbohydrates that release energy slowly. Examples of these include oat and bran-based cereals, wholegrain bread, pasta cooked al dente, and sweet potatoes.

    It’s important to keep active when you’re pregnant – this can reduce your risk of developing gestational diabetes in the first place. Speak to your doctor or midwife if you have any concerns about exercising during pregnancy, or if you haven’t previously been doing any exercise.

    For more information about what to eat and how to get more active, see Related information.


    If you’ve tried to control diabetes by making lifestyle changes but, after two weeks, it hasn’t made any difference, you may need to take medicines. Your doctor will talk to you about the different options available.

    Your doctor may prescribe you insulin, which you will need to take as an injection. They will show you how to inject yourself and give you advice on when to do this.

    Many tablets for diabetes aren’t recommended for pregnant women but your doctor may prescribe you metformin or glibenclamide. These work in different ways to reduce the level of glucose in your blood.

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  • Causes Causes of gestational diabetes

    There are a number of things that can increase your risk of developing gestational diabetes. You’re more at risk if you:

    • are older (over 35) 
    • smoke 
    • are overweight or obese 
    • have previously given birth to a large baby who weighed 4.5kg (10 pounds) or more at birth 
    • have had gestational diabetes before 
    • have a close relative with diabetes, such as a parent, brother or sister 
    • have polycystic ovary syndrome

    The condition is also more common in people with a South Asian, African American, black Caribbean or Middle Eastern background.

  • Complications Complications of gestational diabetes

    Complications affecting you

    Complications that can affect you include the following.

    • Pre-eclampsia: you may develop high blood pressure during your pregnancy. 
    • Polyhydramnios: this is when you have too much amniotic fluid (the fluid around your baby in your womb). It can increase your risk of premature labour. It could also be a sign that your baby is in the wrong position for birth. 
    • Premature labour: giving birth before 37 weeks of pregnancy. 
    • Difficulties giving birth naturally: this is because your baby may grow larger than normal if you have diabetes during pregnancy. The size of your baby will be monitored through your pregnancy. You might need to be induced, which means your doctor will start your labour using medicines. They will discuss this with you. 

    Future risks: there are two future risks that might affect you.

    • You're more likely to develop gestational diabetes if you have another baby you have a higher risk of developing type 2 diabetes later in life.
    • After you’ve had your baby, you’ll need to be checked for type 2 diabetes regularly so that you can get any treatment you need.

    Complications affecting your baby

    Complications that may affect your baby include the following. 
    • Your baby can grow larger than normal. This can make labour and giving birth more difficult, and can increase the risk of shoulder dystocia (where your baby’s shoulders get stuck during birth). Your midwife or doctor will advise you on the best way for your baby to be born safely. 
    • Your baby may have low blood glucose (hypoglycaemia) after birth. This will be monitored and only needs treatment if your baby’s blood glucose drops below a certain level. 
    • Your baby has a higher risk of developing jaundice. This can cause your baby’s skin and eyes to have a yellow tinge. 
    • If born prematurely, there’s a higher chance of your baby having breathing difficulties. This can happen if your baby’s lungs haven’t fully developed when you give birth and can lead to serious complications. 
    • Your baby will have a higher risk of being obese in later life. 
    • Your baby will have a risk of developing type 2 diabetes later in life. 
    • Stillbirth; you’ll be monitored throughout your pregnancy to help prevent this, and other complications.
  • Gestational diabetes after your baby is born Gestational diabetes after your baby is born

    You and your baby will have your blood glucose levels tested shortly after you give birth, to make sure these are in the normal range. Doctors recommend you breastfeed your baby straightaway to keep their blood glucose at a safe level.

    For most women, once their baby is born, gestational diabetes goes away. So you can usually stop taking medicines for gestational diabetes as soon as you give birth. You’ll need to have a blood glucose test at your six-week check-up to ensure that your blood glucose has returned to normal.

    It’s important to keep your blood glucose level under control and carry on with any changes you’ve made to your lifestyle. This is because you have a greater risk of developing type 2 diabetes once you’ve had gestational diabetes. Make sure that you make an appointment to get your blood glucose checked once a year.

    There’s a chance that your blood glucose level could remain high after you’ve given birth. This means you could develop diabetes, even though you’re no longer pregnant. About half of women with gestational diabetes will go on to develop type 2 diabetes within 10 years. You can reduce your risk by improving your lifestyle, for example by being active, eating a balanced diet and maintaining a healthy weight. Your doctor will talk to you about some options to manage the condition.

  • How will gestational diabetes affect the birth of my baby? How will gestational diabetes affect the birth of my baby?


    If your diabetes is well controlled, it shouldn’t affect your baby’s birth. But for a number of reasons, you may need a caesarean delivery.

    More information

    If you have gestational diabetes, you’ll usually be offered to have your labour induced or have a caesarean after 38 weeks. Being induced means your labour is started by your doctor, before your due date.

    You can discuss your options at your antenatal appointments. Your doctor will usually advise you to have your baby in a hospital that has a team experienced in looking after women who have diabetes. Home births aren’t usually an option for women who have gestational diabetes.

    Your blood glucose level will be checked throughout your labour. You may need an intravenous drip (a tube put into a vein in your arm) during labour. This is so you can be given insulin and glucose solution to ensure your blood glucose level remains within the correct range.

    Your doctor will discuss your treatment options with you and help you make preparations for giving birth. Your baby will be continuously monitored throughout your labour to make sure they are safe.

  • What is hypoglycaemia? What is hypoglycaemia?


    Hypoglycaemia (or a ‘hypo’) is when you have very low levels of blood glucose. Your doctor or specialist nurse will explain how to recognise the symptoms of this, and what to do if it happens.

    More information

    You can get hypoglycaemia if you take too much of your medicines for gestational diabetes, or miss a meal after taking your medicines. Symptoms can include:

    • having a faster heartbeat than usual 
    • shaking and trembling 
    • feeling sweaty 
    • feeling confused 
    • a headache

    Your doctor or specialist nurse will explain how to recognise these symptoms and what to do. For example, it’s a good idea to keep a sugary, soft drink with you at all times.

  • Other helpful websites Other helpful websites

    Further information


    • Gestational diabetes. PatientPlus., reviewed 17 March 2015
    • Gestational diabetes mellitus. BMJ Best Practice., published 4 March 2015
    • Diabetes in pregnancy: management from preconception to the postnatal period. National Institute for Health and Care Excellence (NICE), 25 February 2015.
    • Tieu J, McPhee AJ, Crowther CA, et al. Screening and subsequent management for gestational diabetes for improving maternal and infant health. Cochrane Database of Systematic Reviews 2014, Issue 2. doi:10.1002/14651858.CD007222.pub3
    • Common pregnancy complaints and questions. Medscape., published 19 December 2014
    • Glycaemic index (GI). British Dietetic Association., reviewed December 2013
    • Having a baby after age 35. American College of Obstetricians and Gynecologists., published September 2015
    • Polyhydramnios. The Merck Manuals., published January 2014
    • Gestational diabetes. American College of Obstetricians and Gynecologists., published September 2013
    • Farrar D, Duley L, Medley N, et al. Different strategies for diagnosing gestational diabetes to improve maternal and infant health. Cochrane Database of Systematic Reviews 2015, Issue 1. doi:10.1002/14651858.CD007122.pub3
    • Neonatal jaundice: step-by-step diagnostic approach. BMJ Best Practice., published 24 August 2015
    • Bain E, Crane M, Tieu J, et al. Diet and exercise interventions for preventing gestational diabetes mellitus. Cochrane Database of Systematic Reviews 2015, Issue 4. doi:10.1002/14651858.CD010443.pub2
    • Respiratory distress syndrome in neonates. The Merck Manuals., published January 2015
    • Gestational diabetes care to expect before and after giving birth. Diabetes UK., accessed 9 November 2015
    • Diabetes in pregnancy. PatientPlus., reviewed 17 March 2015
    • Hypoglycaemia. PatientPlus., reviewed 5 April 2013
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    Reviewed by Rachael Mayfield-Blake, Bupa Health Content Team, December 2015.

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