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Gestational Diabetes Mellitus-What Is It And Who Is At Risk

Some women may develop diabetes mellitus for the first time when they become pregnant and the terms used for this are either pregnancy onset diabetes or gestational diabetes. Screening for this is done on women who are considered to be in the higher risk categories, although they themselves will often not experience too many symptoms; however there is a potential risk of macrosomia.

Macrosomia is the term used to describe a baby who has a high birth rate, which increases the risk of complications when giving birth. This can be seen during a pregnancy scan from around 20 weeks onwards. At this stage it is possible for the ultrasound scan to show that the foetus is larger than normal for its gestational age.

If this does become evident during an ultrasound scan, then screening for gestational diabetes will be recommended. The screening is a glucose tolerance test, which involves doing a blood test after fasting over night and comparing this to a blood sample taken just after the patient drinks a glucose rich drink.

1. Gestational Diabetes-What Are The Possible Risks To Baby

The potential risks to baby when gestational diabetes has been diagnosed are:

• Still birth
• Neo-natal death
• Heart problems
• Difficulty in breathing
• Increased risk of obesity
Increased risk of diabetes
• Macrosomia
• Risk of hypoglycaemia

Macrosomia is defined when the birth weight exceeds 9 pounds, 5 ounces (4.5kg) and this condition may result in many women needing to give birth with caesarian section. Alternatively the decision may be to induce birth before the due date so that baby is still small enough for an uncomplicated delivery.

There is a risk of hypoglycaemia to babies shortly after birth, as they may experience a sudden drop in glucose levels which if not treated could lead to coma and even death. Many babies of mothers with diabetes will have to have special care to manage cardiac or breathing problems.

2. Gestational Diabetes-Who Is At Higher Risk Of Developing GDM?

Women who are overweight, particular obese women run a higher risk of developing GDM. If there is a family history of diabetes or you have previously given birth to a large baby, then the risk is heightened. Black women, Middle Eastern women and Asian women are more likely to be at risk.

gestational diabetes

3. What You Can Do To Help Reduce The Risk

Today we have a growing awareness of the importance of a healthy pre-conception lifestyle. If you are planning to become pregnant you can help yourself and the baby you hope to conceive by taking the time to reduce, and ideally finish unhealthy habits, such as smoking and drinking alcohol.

If you need to lose some weight, find a way that you enjoy to exercise, as this is by far the easiest way to change your lifestyle habits. Walking in nature is a gentle and enjoyable way for many women to start to become healthier again. Remember that losing weight in a healthy way may also increase your fertility. Women who are overweight and obese often suffer from hormonal imbalances which affect their fertility.

Other articles from this series:

Midwife sonographer facilitated

Consultant Led, Centre of Medical Excellence 


All articles on the blog and website are intended as information only. Please do not consider any of the information provided here as a substitute for medical advice. At all times seek medical advice directly with your own doctor and medical team.


This website was formerly Merrion Fetal Health. The clinic has undergone a rebrand and is now known as Merrion Ultrasound.