Gestational diabetes: how can it affect pregnancy?

What is gestational diabetes?

Gestational diabetes is a condition where a pregnant woman’s blood sugar levels are high only during pregnancy. The condition improves when the baby is born. Gestational diabetes is very common, affecting approximately 16% of pregnancies in the UK.

What causes gestational diabetes?

Insulin is the hormone produced in the body that brings blood sugars down, moving sugar from the blood stream in to all the tissues and organs.  During pregnancy, the hormones from the placenta make the body more resistant to the action of the insulin, meaning that sugar remains higher in the blood and for longer.   

This occurs in all pregnancies. However, in some women insulin resistance is great and the blood sugars reach a particularly high level, causing gestational diabetes.

What are the signs of gestational diabetes? How is it diagnosed?

Unfortunately, gestational diabetes does not display any symptoms.  It is normally detected through a planned test or when a midwife finds glucose in your urine during pregnancy.

Gestational diabetes is diagnosed using an oral glucose tolerance test. During this test, you are asked to drink a sugary drink after an overnight fast and your blood glucose is measured at baseline. The blood glucose will then be measured again at 1 and/or 2 hours after you take the drink. Depending on those blood sugar levels, you may be diagnosed with gestational diabetes.

Who is at risk of gestational diabetes?

There are a number of factors that make women more at risk of developing gestational diabetes.  These are as follows:

• Having a family history of diabetes (particularly within the mother, father or any siblings)
• Being from certain ethnic groups (particularly Asian and Black populations)
• Being an older mother (over the age of 40)

There is also a 90% chance of developing gestational diabetes in a pregnancy if you have suffered from it in a previous pregnancy.  However, many women develop gestational diabetes without any prior risk factors.

What are the risks for the baby associated with gestational diabetes?

Having a large baby is the main risk associated with gestational diabetes. Having a large baby leads to an increased risk of difficulties in labour, particularly increasing the risk of shoulder dystocia, where the baby’s shoulder or arm may get stuck.

Additionally, there is also an increased chance of the mother having to deliver the baby via caesarean section.

If the mother has gestational diabetes during pregnancy, there is an increased risk of the baby having a low blood sugar at birth. This means that they may need some extra feed or a drip containing sugar. In rare cases, the baby may need to be admitted to the neonatal unit.

Gestational diabetes is also associated with an increased risk of pre-eclampsia, where there is high blood pressure and protein in the urine in the mother and the baby’s growth may be affected.

High blood sugar surrounding the baby also affects its long -term development, increasing the risk that they may be obese and/or develop diabetes in later life.

However, controlling diabetes during pregnancy can reduce all of these risks.

What about the implication for the mother?

Women with gestational diabetes have a 50% chance of developing diabetes (usually type 2 diabetes) within 10 years of pregnancy.  It is therefore crucial that they are checked annually after pregnancy to try to prevent diabetes and detect it early if it does develop.

How is gestational diabetes managed?

It is essential for an expectant mother who is suffering from gestational diabetes to try to manage her pregnancy well, with medical aid. Management will involve managing her blood sugars and monitoring the baby closely.

For many women, their blood sugars can be controlled with some diet changes and mild exercise.  However, a proportion of women require medication. Metformin is a tablet that is usually the first line treatment, but in some cases insulin injections will be required to treat the condition.

The baby should have regular scans from about the 28^th week of pregnancy.  Decisions about timing and mode of childbirth are then made by looking at the baby’s growth and how well controlled the mother’s blood sugars are, usually after discussion between the woman’s obstetrician and diabetes specialist.  

Is there anything else I need to know?

In some cases, there can be other causes for high blood sugars in pregnancy.  Some women have underlying undiagnosed diabetes, including genetic diabetes, which is identified for the first time in pregnancy.  A careful review of the woman’s medical and personal history, as well as her blood sugar levels, can help in determining if there is likely to be an underlying diabetes condition.

If you are suffering from gestational diabetes and would like to book a consulation with Dr Scott, you can do so via her Top Doctors profile.