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By Dr Janice TUNG, Associate Consultant and Associate Professor Tan Thiam Chye, Visiting Consultant, Department of Obstetrics and Gynaecology, KK Women's and Children's Hospital

Gestational diabetes can affect any pregnant woman, and can have an impact on the baby's health. This guide will help you understand and manage this condition.

What is Gestational Diabetes?

what is gestational diabetes

Diabetes (gestational diabetes mellitus, or GDM) can occur in pregnancy when the body produces inadequate amounts of the hormone insulin to deal with sugar control. As a result, blood sugar levels may rise.

The good news is that the condition often resolves after delivery. For some women, the condition may persist and long-term follow-up and treatment will be needed.

GDM can be identified via an oral glucose tolerance test (OGTT) and effectively managed in pregnancy. A proactive treatment plan helps ensure a smooth pregnancy and delivery for you, and protects the health of your baby.

Related: All You Need to Know About Gestational Diabetes

How Does It Affect Your Baby?

how does GDM affect baby

Untreated GDM is associated with elevated blood glucose levels that can cause the following issues for you and your baby.

  • Excess growth (macrosomia)

GDM may cause your baby to be very big (> 4kg) and have extra fat. This makes delivery more challenging as a bigger baby may not be able to pass through the birth canal, necessitating a Caesarean section for delivery.

  • Premature delivery

GDM may increase your chances of early labour and delivery. Alternatively, the doctor may recommend an earlier delivery because the baby is too large.

  • Respiratory distress syndrome

This is a condition that makes breathing difficult. Babies with this syndrome may need help breathing until their lungs mature. This condition should disappear once your baby's lungs get stronger.

  • Low blood sugar

Some babies of mothers with GDM may develop low blood sugar (hypoglycaemia) shortly after birth because their own insulin production is high. Severe episodes of hypoglycaemia may cause the baby to get seizures. However, prompt feedings and sometimes an intravenous glucose solution often returns the baby's blood sugar level to normal.

  • Increased risk of sudden foetal death or stillbirth

  • Type 2 Diabetes later in life

Babies of mothers with GDM have a higher risk of developing obesity and Type 2 diabetes later in life.

Related: Pregnant When You Have Diabetes: A Checklist

Complications That May Affect a GDM Mother

complications for a GDM mother

If you have GDM, these are the risks you may encounter:

  • High blood pressure and pre-eclampsia

This is a serious complication of pregnancy that causes high blood pressure and can threaten both your and your baby's life.

  • Future diabetes

Mums who've had GDM before are more likely to develop it again during a future pregnancy. In addition, they're also more likely to develop Type 2 diabetes as they get older.

The Symptoms

Most women with GDM don't have noticeable signs or symptoms. You'll be tested for the condition as part of your prenatal care.

Related: Coping With the Unexpected: Pregnancy Complications

Testing For GDM — Oral Glucose Tolerance Test (OGTT)

The Oral Glucose Tolerance Test (OGTT) requires you to drink a glucose solution after a night of fasting, followed by the drawing of blood samples at the onset, at one and two hours later. The test is considered abnormal if the glucose levels are above a certain level.

Normal OGTT values are:

  • Fasting glucose level of between 3.5 and 5.5 mmol/L
  • 2-hour glucose level of < 7.0 mmol/L

When is the Test Done?

The test is usually offered to all pregnant women between weeks 24 and 28 of pregnancy.

Related: 3 Habits You Need to Manage Your Diabetes

The Risk Factors

GDM risk factors

There are several risk factors that make one more prone to developing GDM. These include:

  • Being above 35 years of age
  • If there are persistent traces of glucose on at least two episodes
  • Being obese (> 80kg)
  • Being on long-term steroids
  • Having a family history of diabetes especially among immediate family members
  • A past history of diabetes in pregnancy
  • A past history of big babies (> 4kg)
  • Suspected macrosomia — when the baby is considered bigger than what is expected at that particular gestational age
  • History of unexplained stillbirth or bad obstetric history

Managing GDM

managing GDM

Treating GDM boils down to one thing: controlling your blood glucose levels so that they don't get too high. This can be done by eating well, exercising and if prescribed, taking insulin or other medication. Not every woman with GDM needs insulin or medication.

Related: How to Have a Healthy Pregnancy with Diabetes

Eating Well

A registered dietician can help create a meal plan that can control your blood glucose levels and keep it in the healthy, normal range. This plan will most likely take into account your overall health, physical activity and what you like to eat.

Related: How to Have a Healthy Pregnancy When You Have Diabetes


Your body uses more glucose when exercising, helping to lower your blood glucose levels and making you less insulin resistant. Discuss the type of exercise with your doctor first and try to get 30 minutes of exercise a day.

Insulin/Medication: It's always best to try to control blood glucose levels through diet and exercise. However, if extra help is needed, your doctor may prescribe insulin or other medication to help your body regulate its blood glucose levels. Insulin injections will be given in more severe cases.

Related: Pregnancy Exercises

Will GDM Go Away?

GDM often resolves after you deliver your baby. Your doctor will check your blood glucose levels about six weeks after delivery to check if it's in the normal range again.

If you've been diagnosed with GDM, don't worry. Tap into the experience of the team of health caregivers who will monitor both you and your baby. Take the necessary steps to control GDM as soon as you're diagnosed. Following your doctor's advice, eating healthily and exercising will ensure both you and your baby remain healthy and that this is just a small blip on the radar.

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Visit Parent Hub, for more useful tips and guides to give your child a healthy start.

Read these next:


The New Art and Science of Pregnancy and Childbirth 2008, World Scientific

Healthy Start for your Pregnancy 2012, Health Promotion Board Singapore

Learn more at and embark on a happy, healthy and active pregnancy.