Diabetes in pregnancy

Diabetes in pregnancy – also known as gestational diabetes – refers to high blood sugar (glucose), which develops in pregnancy. It can happen during any stage of pregnancy but is more common in the second and third trimester¹. It affects women who don’t already have another type of diabetes², and usually disappears after you’ve given birth.

It’s the most common medical condition to affect pregnant women, occurring in 10-20% of pregnancies in England³.

With proper management, most women with gestational diabetes go on to have healthy pregnancies and healthy babies⁴.

Why does it happen?

During pregnancy, your placenta produces hormones that can lead to an increase in blood sugar levels. Usually, the body can produce more insulin to handle this increase, but in some cases, it doesn't – resulting in gestational diabetes.

How can it affect my pregnancy?

Occasionally gestational diabetes can lead to complications in pregnancy or during birth, especially if it goes unrecognised or isn’t well controlled⁴.

Complications can include:

• Your baby growing larger than usual (macrosomia) – this increases the likelihood of an induced labour or a caesarean section. It also increases the chance of difficulties during labour, such as shoulder dystocia (where your baby’s shoulder gets stuck).
  
  
• Premature birth – giving birth before 37 weeks.
  
  
• Pre-eclampsia – a condition that causes high blood pressure during pregnancy and can lead to pregnancy complications if not treated.
  
  
• Polyhydramnios – too much amniotic fluid (the fluid that surrounds the baby) in the womb, which can cause premature labour or problems at delivery.
  
  
• Your baby developing low blood sugar (hypoglycaemia) or yellowing of the skin and eyes (jaundice) after birth, which may require treatment in hospital.
  
  
• Your baby may need additional care once they’ve been born, possibly in a neonatal unit⁴.
  
  
• Increased risk of miscarriage.
  
  
• The loss of your baby (stillbirth) – though this is rare¹.
  
  
• Elevated blood sugar levels can affect your immune system, which can make it more challenging for your body to fight off infections. For example, you might be more susceptible to UTIs, vaginal infections and skin infections.
  
  
• An increased risk of having gestational diabetes in future pregnancies (more than one in three women will get gestational diabetes again⁴) and developing type 2 diabetes in the future.
  
  
• Later in life, your baby may have a higher risk of being overweight or obese, and developing type 2 diabetes. As your child grows, managing their weight, eating healthily and being physically active will reduce this risk.

Read more > Diabetes in children

Working closely with your healthcare team to keep blood sugar levels within your target range will lower the chance of these complications and increase your chances of a healthy pregnancy and baby. This can include making dietary changes, physical activity, and sometimes taking medication.

Symptoms

Gestational diabetes doesn’t usually cause any symptoms¹. Most cases are only discovered when your blood sugar levels are tested during screening for gestational diabetes.

If your blood levels are too high (hyperglycaemia), you may develop symptoms such as:

• increased thirst
• needing to urinate more often than usual
• a dry mouth
• tiredness
• blurred eyesight
• genital itching or thrush.

Some of these symptoms are common during pregnancy and aren’t necessarily a sign of gestational diabetes¹. Make sure to speak to your midwife or doctor if you're worried about any symptoms you're experiencing.

When do I get tested for gestational diabetes?

You’ll be asked questions during your first antenatal appointment (also called your booking appointment), usually around 8-12 weeks of your pregnancy, to assess whether you have an increased risk of gestational diabetes.

If you have one or more risk factors, you’ll be offered a screening test – also known as the oral glucose tolerance test (OGTT), which takes about two hours to complete. It’s usually conducted at the clinic or hospital where you’ve been receiving antenatal care, or a specialist diabetes clinic.

It involves having a blood test in the morning after fasting for 8-10 hours (you can usually drink water but check with the hospital if you're unsure). After fasting, you’ll drink a glucose (sugary) drink before resting for two hours. A blood sample will then be taken to see how your body processes the glucose.

The OGTT is typically conducted between 24-28 weeks of pregnancy. However, if you’ve experienced gestational diabetes in a previous pregnancy, an earlier OGTT will be offered soon after your booking appointment, with an additional OGTT at 24-28 weeks if the first test results are normal¹.

Top tip: Pack a snack to have afterwards, as you’ll likely be hungry.

During your pregnancy

If your fasting blood sugar level is 5.6mmol/l or above, or if your 2-hour post glucose blood sugar level is 7.8mmol/l or above, you’ll be diagnosed with gestational diabetes and be referred to a joint specialist diabetes and antenatal clinic for your care⁵.

Your healthcare team may include a:

• Doctor specialising in diabetes.
• Obstetrician (a doctor specialising in pregnancy, childbirth and the postpartum period).
• Specialist diabetes nurse.
• Specialist diabetes midwife.
• Dietitian.
• Community midwife.

You’ll need to attend more frequent antenatal appointments to keep an eye on you and your baby and will be offered extra ultrasound scans to monitor your baby’s growth more closely.

Your healthcare team will recommend the best treatment for you and advise on how you can test your blood sugars at home and follow a healthy diet⁴.

Top tip: Walking for 30 minutes after a meal can help with controlling your blood glucose level⁴.

You might be able to reach your target blood sugar levels with diet and exercise alone, or you might be prescribed tablets and/or insulin injections to help⁴. If your glucose level is very high at the time of diagnosis, you may be offered treatment straight away, in addition to making changes to your diet and exercise.

With proper management, most women with gestational diabetes go on to have healthy pregnancies and healthy babies⁴.

Labour and birth

You’ll discuss your birth options with your healthcare team throughout your pregnancy, which include waiting for labour to start, having an induction of labour, or having a planned caesarean birth. This depends on your individual circumstances.

Due to the potential complications and risks involved, you’ll be advised to have your baby in a hospital with a consultant-led maternity unit and a neonatal unit⁴.

During labour, closer monitoring of blood glucose levels is needed and it may be that an intravenous drip of insulin as well as glucose is needed, to enable careful control of blood glucose levels.

After birth

Unless your baby needs extra care, they will stay with you. You can usually have skin-to-skin contact straight away if you choose. Occasionally your baby might need to be looked after in the neonatal unit if they’re unwell or need extra support. It’s recommended your baby has their blood glucose level tested a few hours after birth to make sure it’s not too low⁴, in addition to the usual newborn checks.

Your blood glucose levels usually return to normal once your baby is born and any medication is usually stopped immediately after giving birth. You should be offered a fasting blood glucose test 6-13 weeks after birth. A small number of mothers continue to have high blood glucose levels and will be offered further tests for diabetes.

Up to 50% of women who have had gestational diabetes develop type 2 diabetes within the following 5 years⁴. You’ll therefore be advised to have a test for this every year.

Feeding your baby

Breastfeeding is safe to do. However, your baby will have a higher risk of low sugar levels after birth, so – whether you decide to breast or bottle feed – you should start feeding as soon as possible after birth, and then every 2-3 hours to help your baby’s blood glucose stay at a safe level⁴.

You might be advised to hand express and give your baby this early breast milk (colostrum) in addition to breastfeeding directly. It’s safe to express colostrum in pregnancy from 36 weeks onwards⁴ and store it for use after giving birth. This can help, should you experience difficulties breastfeeding after birth. Your healthcare team will support you in feeding your baby – including advice on how to store breast milk safely.

Diabetes Prevention Programme

If you’ve had gestational diabetes, you’ll have an increased likelihood of developing gestational diabetes in future pregnancies. You’ll also have a higher risk of developing diabetes and cardiovascular disease after pregnancy³.

Long term follow up assessments will be put in place by your healthcare team to manage these risks, including referral for support to reduce the development of diabetes, such as the Diabetes Prevention Programme. For example, you can learn how to understand food labels, control portion sizes and make healthier everyday swaps – all while juggling a busy lifestyle with children.

What increases your risk?

• If you’re over 40¹.
• Your body mass index (BMI) is above 30.
• You previously had a baby who weighed 4.5kg (10lb) or more at birth¹.
• You had gestational diabetes in a previous pregnancy.
• One of your parents or siblings has diabetes.
• You’re of south Asian, Black, African-Caribbean or Middle Eastern origin (even if you were born in the UK)¹.
• You’ve had a gastric bypass or other weight-loss surgery.

If any of these apply to you, you should be offered screening for gestational diabetes during your pregnancy.

Lowering your risk

It’s not always possible to prevent gestational diabetes, but there are some things you can do to reduce your risk, such as:

• Maintain a healthy weight: If you’re planning to become pregnant, aim for a healthy weight before pregnancy. Diabetes UK offers a lot of helpful information and support. During pregnancy, follow your healthcare team’s guidelines regarding weight gain.
  
  
• Healthy diet: Eat a balanced diet rich in fruits, vegetables, whole grains, and lean proteins. Limit foods high in sugar and refined carbohydrates. Read our tips on how to get more fruit and vegetables into your diet.
  
  
• Regular exercise: Enjoy regular physical activity, such as walking, swimming, or antenatal yoga, as it can help regulate blood sugar levels.
  
  
• Monitor blood sugar levels: If you’re at risk, your healthcare team might recommend regular blood sugar testing to catch any issues early.
  
  
• Regular antenatal care: Attend all antenatal appointments so your healthcare team can monitor your health and address any concerns promptly.

While these steps can help reduce the risk, they don’t guarantee prevention, especially if there are genetic factors involved. Always consult with your healthcare team for personalised advice.

Is the care plan different if I have diabetes before pregnancy?

It is. The NHS website, Guy’s and St Thomas’ NHS Foundation Trust and Diabetes UK provide helpful information on diabetes and pregnancy, including:

• How to prepare for pregnancy.
• Your diabetes treatment in pregnancy.
• Knowing the risks of possible complications.
• After your baby is born.
• Checking your blood sugar and medication.
• Taking folic acid.
• Getting your eyes and kidneys checked.
• Labour and birth.
• After birth.

Reach out if you’re feeling low

Please don’t forget to check in with how you’re feeling before, during and after your pregnancy. If you’re ever feeling low, or like you’re not yourself, please seek support. There are charities available to help, as well as local support groups and online resources. Your GP can recommend the best next steps for your specific needs and situation. Partners should also reach out should they need support too.

Useful links

• BMI healthy weight calculator – NHS
• Diabetes – Staying Healthy
• Exercise hub providing information on how to fit exercise into a busy lifestyle, including a weekly activity planner, podcast and exercise videos. There’s also a helpline available on 0345 123 2399 if you want support to become more active – Diabetes UK
• Mental health support to women and families before, during and after pregnancy – Maternal Mental Health Alliance
• List of perinatal mental health support and services – Mind
• Provider contact details – Healthier You NHS Diabetes Prevention Programme
• Weight loss and diabetes information, including meal plans, a weight loss planner and emotional support – Diabetes UK

References

1. Gestational diabetes – NHS
2. Gestational diabetes – Diabetes UK
3. National Gestational Diabetes Mellitus Audit – NHS England 
4. Gestational diabetes – Royal College of Obstetricians & Gynaecologists
5. Gestational Diabetes Tests – Diabetes UK